Introduction
Metabolism is a dedicated network of enzyme and metabolite-derived mechanisms that is a hallmark of life activities. A healthy metabolism is a basic necessity for a healthy life that depends on lifestyle, energy intake, and expenditure. A balanced lifestyle comprising healthy eating habits, exercise, sleep cycle, and behavioral features is the utmost regulator of healthy body weight and robust metabolism.
The present-day world is challenged by an increasing prevalence of overweight and obesity, amounting to epidemic proportions. This creates a public health concern and points to our lack of success in achieving healthy population indices in terms of healthy body weight maintenance.[1] Increased weight parallels with several comorbidities such as type-2 diabetes, some types of cancers, cardiovascular disorders, liver and kidney diseases, digestive problems, sleep apnea, osteoarthritis, etc.[2][3][4][5][6] Recent research indicates that the inability to maintain a healthy weight perturbs the body's metabolic and immunological axis, increasing the risk for severe illnesses such as COVID19 and other infectious diseases.[1][7] It is notable that absolute weight loss with long-term maintenance directly correlates with improvements in all health risk factors.[8]
Maintaining a healthy body weight, especially after weight reduction, requires equalized input and energy output to regulate optimal metabolism. This comprises a concerted regulation of enzyme activities, ATP synthesis, utilization, hormonal functions, neurological and muscular activities, etc. However, a general preference for high-tasting vis-à-vis less nutritious food and a sedentary lifestyle has led to a global increase in weight and also a reduced tendency of long-term maintenance of a healthy weight after effective weight loss.[9]
It is believed that weight loss at a slow rate is better sustained than weight loss more rapidly. However, scientific evidence correlates that greater initial weight loss is positively related to long-term weight maintenance. This follows through a metabolic adaptation process, consequently leading to healthier metabolic functions. Nonetheless, healthy weight maintenance achieved through weight loss regimes also requires care and treatment, usually through diet regimes or restrictions and exercise. However, no specific diet or exercise program has been truly established as a successful regime in weight maintenance. Presently, weight management strategies underline the significance of attaining a 5% weight loss to maintain a healthy metabolism.
Prior to understanding the consequences of weight loss on metabolism, it is imperative to recognize that at the metabolic level, weight loss is a continuous metabolic adaptation process progressing through many biochemical and physiological changes involving the role of hormones, enzyme functions, metabolite effectors, and bioenergetics.
Maintaining a healthy weight is challenging. It is shown that most individuals tend to have regained a significant amount of the lost weight within a year after weight loss. With this increased prevalence of recidivism, weight management is viewed as a chronic issue. Hence, long-term care is expected for weight management and maintenance after weight loss, and programs of over a year are currently recommended by the guidelines.[10]
This review will focus on the metabolic parameters (initiators, activators, pathways, and endpoints) achieved consequent to various weight-loss regimes, i.e., dietary modulations, exercise, drug, and surgical intervention aimed at improving metabolic health and long term healthy weight maintenance.
Function
Metabolism is a group of processes through which food is converted into energy to help maintain bodily function. The energy generated through biochemical pathways is usually in the form of Adenosine triphosphate (ATP). A continuous supply of ATP to meet the body's energy demands during activity and rest is fundamental to the metabolic processes that sustain life. During the resting stage, the body requires energy to support activities such as breathing, maintaining blood circulation, brain function, cellular growth and repair, basic hormonal and neurological changes, etc.[11]
The calories needs for maintaining basal (resting phase) metabolism is called basal metabolic rate (BMR). BMR increases with a decrease in body weight to about 0.02 kcal/min, corresponding to each 1% decrease in body weight. Healthy body weight is calculated by the measurement of body mass index (BMI). It assesses the bodyweight of an individual relative to their height and hence provides a more distinctive account of body fat content than just the weight. Though BMI does not directly measure body fat, it is a useful and inexpensive screening method for clinical and research purposes. For adults, BMI is categorized into four ranges and indicates varying levels of health risks. For Asians, BMI ranges are different.
- BMI below 18.5 indicates underweight
- BMI range of 18.5-24.9 indicates a normal/ healthy state
- BMI range of 25-29.9 indicates overweight
- BMI equal to or higher than 30 is considered obese
Obesity is, however, sub-classified as class-1 obesity (BMI of 30 to < 35): class-2 obesity (BMI of 35 to < 40) and class-3 obesity (BMI of 40 or higher)
- BMI for an individual is calculated by any of the following equations:
- BMI = [weight (kg)/height (m)]
- BMI = [weight (lb)/height (in)] x 703
BMI corresponding to the normal range is associated with health compared to underweight, overweight, or obese ranges. Too little or too much body fat in underweight and overweight/obese reflects a risk of disease predisposition.[12] A healthy metabolism is maintained through normal homeostasis and appropriate regulation of blood pressure, blood glucose and lipid profiles, etc. At the metabolic level, weight loss of 5% of initial weight is associated with improvement in biochemical and physiological parameters of the body and thus health benefits. Furthermore, weight loss programs are directed towards reducing weight by 1 to 2 pounds/week (approximately 0.5 to 1 kg/week).[10] Recommended weight reduction prevents drastic changes in metabolism and is associated with better long-term weight maintenance.[13]
Bodyweight, as estimated by BMI and body fat distribution and composition when assuming a condition of overweight or obesity, impacts metabolic health unfavorably. Notably, some individuals can be metabolically healthy despite being overweight and are categorized as metabolically healthy obese (MHO). MHO indicates the absence of hypertension, dyslipidemia, type2 diabetes, or insulin resistance and does not present health risks.[14] Contrastingly, individuals categorized as healthy based on BMI values can demonstrate higher metabolic risks and are known as metabolically obese normal weight (MONW).[14] The individual disparity in body weight correlation to health can be challenging, which assumes that less weight is healthy and more unhealthy. Hence, it requires practitioners to carefully assess overall metabolic health and BMI to suggest a weight maintenance regime to the patients.
Weight management or reduction is considered a standard regime to overcome high body mass index and reduce predisposition to metabolic, inflammatory, and infectious diseases. Managing bodyweight impinges on modulating the metabolism through diet and calorie restriction, physical activity, intermitted fasting, sleep cycles, etc. Herein, we will discuss the metabolic regulation and consequences of different weight loss regimes.
Calorie Restriction and Dietary Modifications for Weight Loss and Metabolic Consequences
Metabolism constitutes a multitude of biochemical reactions to derive energy from food and drink. The gain of weight usually occurs through metabolic derangement wherein food intake is more than the energy expenditure from metabolic activities, leading to accumulation of excess energy in the form of fat deposition in adipose tissues.
Many dietary regimes have been developed to substantiate weight loss as well as maintenance of lost weight. However, none presents to be universally effective. The manifestation of individual differences can be due to lifestyle choices, eating habits, and metabolic variations. According to the American College of Cardiology/American Heart Association Task Force guidelines, a hypocaloric diet (calorie restriction) as a lifestyle intervention method has been proposed to induce a negative energy balance.[15]
Besides efficiently inducing sustained and long-term weight loss, calorie restriction supports metabolic health, prevents diseases, and delays aging.[16] Calorie restriction generates an overall lower metabolic rate and a gradual decline in energy expenditure to match the intake eventually. This helps to generate a metabolic rate to maintain lower body weight. At the initial phase of calorie restriction, reduction in energy intake is more drastic than energy expenditure, inducing an energy deficit and weight loss. Since energy expenditure (EE) corroborates to body mass, weight loss, in turn, decreases the EE. Over time calorie restriction regime establishes an energy intake and EE balance, reaching an energy balance with reduced body weight. This decline in EE proportionate to body mass alterations is termed metabolic adaptation. During the calorie restriction regime, the metabolic adaptation during rest (basal metabolism) and activity correlates with weight loss.[17] This is maintained not just through changes in metabolic processes but also compensatory behavioral mechanisms to conserve energy. It is proposed that circulating hormones such as leptin, thyroid hormone, and insulin may mediate calorie restriction responses by influencing heart rate, blood pressure, and sympathetic nervous system.[18] Metabolic adaptation is demonstrated to be specific to the calorie restriction regime since exercise-induced weight loss does not follow metabolic adaptation.[19]
Calorie restriction-induced slowing down of metabolic rate also limits the mitochondrial generation of reactive oxygen species (ROS). ROS is disruptive to molecular and cellular structures and functions of the body. Diminished ROS production due to the slowing down of metabolism alleviates homeostasis and functional impairments.[20] Thus, calorie restriction-induced weight loss consequently improves metabolic health and reduces oxidative damage at the cellular level, thus enhancing the quality of life and lifespan.[17]
Another challenge faced by overweight and obese individuals is the impairment of metabolic flexibility, where the body cannot switch the use of metabolic substrates depending upon the need, nutrient availability, and environmental cues.[21] Metabolic inflexibility also underpins the development of chronic health issues. Often, weight reduction regimes harness the metabolic flux to be channelized towards the use of fatty acid substrates. Thus weight loss becomes harder in patients who have developed metabolic inflexibility. During weight loss and maintenance, cellular metabolic processes such as glycolysis and fatty acid oxidation are lowered. Studies have demonstrated that cellular dysregulation of the tricarboxylic acid cycle and substrate switching between glucose and fatty acids play a role in obesity and the development of chronic disease and metabolic syndrome.[22][23] Overweight and obese people demonstrate an overall improvement in metabolic flexibility after weight loss.
Recently, intermittent fasting, also known as time-restricted feeding, has been somewhat effective in weight loss. Intermittent fasting is proposed to affect human circadian rhythms, sleep patterns, lifestyle behaviors, and intestinal microflora.[24][25][26] Feeding regimes that restrict or exclude nighttime eating patterns leading to long fasting intervals may improve metabolic health. These feeding regimes are non-interventional approaches for enhancing the general well-being of the population and are in the interest of public health.
The alternating fasting and feeding cycles stimulate specific biochemical reprogramming directed to utilize stored energy during the fasting periods termed fasting physiology. It is conjectured that repair mechanisms integral to fasting-refeeding are optimally active during the fasting period. It is thus imperative that periodic and intermittent fasting may trigger factors that help enhance the general health of the individuals. Experimental approaches have demonstrated that combining calorie restriction with intermitted fasting may facilitate fasting physiology to be triggered sooner compared to the regime of consuming high calories.[27] Also, regulating the food intake timings may induce fasting physiology after feeding cycles on a daily basis. It is thus conducive that periodic and intermittent fasting may trigger factors to enhance general health.
Metabolic Effects of Weight Loss Through Physical Activity and Exercise Training
Moderate to intense physical activities daily effectively maintain body structure and weight after healthy weight has been achieved. Many weight maintenance regimes follow exercise and resistance training as mainstream mechanisms towards controlling unhealthy weight regain. Exercise stimulates a negative energy balance and induces a restructuring of body fat.[28] This subsequently promotes an increase in muscle mass, which can be maintained through regular exercise training besides healthy eating habits, optimal sleep cycles, and relaxation. The biochemical mechanisms modulated through exercise include activation of AMP kinases, uptake of substrates from plasma, beta-oxidation of fats, lipid degradation, and mitochondrial functions. Long-term training eventually leads to increased respiratory and cardiac capacity, better insulin sensing, reduced lipids concentration in plasma and tissues, enhanced oxidative capacity of mitochondria, and overall optimal metabolic functions. However, oxidative stress is induced during physical activity. Though oxidative stress is a detrimental mediator of exercise, it serves as a necessary juncture to facilitate metabolic adaptation through increased mitochondrial function and the anti-oxidative capacity of the body. This phenomenon is called metabolic hormesis.[29]
Skeletal muscle contraction constitutes most substrate channelizing mechanisms during exercise to generate a continual supply of ATP. Since muscle reserves for ATP are small, maintaining the ATP resynthesis rates to match muscle contraction is necessary. Reducing equivalents to support ATP synthesis are obtained from carbohydrates and fat metabolism. This increases the phosphocreatine and glycogen breakdown, thus activating both aerobic and anaerobic respiratory pathways.[30] In addition, the intensity of exercise dictates the amount of ATP needed to fulfill the physical activity demand. Hence, the contribution of aerobic and anaerobic pathways is determined by the duration and intensity of the exercise regime.[31]
Exercise-mediated weight loss and maintenance is considered a prime mechanism in sports physiology to maintain low body fat and retaining lean mass, facilitating an optimized body composition.[32] Higher lean body mass composition is advantageous in various sports and improves strength to mass ratio, swift mobility, and body structure. However, this requires an overall energy restriction that leads to alterations in hormone concentrations, mitochondrial mechanisms, and EE from a metabolic standpoint. Less body fat and low-calorie intake indicate energy unavailability, substantiating a homeostatic endocrine response towards conserving energy and promoting energy intake.[33] Due to a change in energy metabolism, EE is structured to minimize energy deficits and weight loss, thus promoting weight regain.
Pharmacological and Surgical Intervention For Weight Loss and Metabolic Effects
Although lifestyle changes, dietary modulations, and physical restraint training are the fundamental measures of weight loss, pharmacological and surgical interventions are now becoming common for therapeutic purposes. However, these interventions are limited by their side effects, surgical risks, and efficacy.
Recent advancements in technologies and metabolomics have helped our understanding of the mechanistic pathways and metabolites that are mediators of an increase in BMI and weight gain. However, only five drug therapies have been approved for obesity treatment thus far.[34] These therapies are based on the use of analogs that manipulate gut hormones facilitating weight loss. Presently, glucagon-like peptide-1 (GLP-1) analogs are used as monotherapy, unimolecular agonists for gastric inhibitory peptide receptor (GIP), GLP-1 receptor, or glucagon receptor are used to induce weight loss. Furthermore, leptin analogs, ghrelin antagonists, amylin mimetics and melanocortin-4 receptor (MC4R), and neuropeptide Y (NPY) antagonists that suppress appetite have demonstrated success in preclinical and clinical trials.[35]
Recently blood metabolic signatures of adiposity associated with lifestyle factors have been identified. Hence, drug design and repurposing of drugs for weight management have taken a faster pace. The drugs used in the weight loss regime, such as selective inhibitors of pancreatic lipase, stimulators of noradrenaline release leading to the suppression of appetite m, combination drugs to enhance satiety by increasing energy expenditure, thus reducing food intake, have shown an overall success in weight management.[35][36][37][38] However, drug and surgical interventions have shown enhanced benefits for weight management after weight loss when combined with lifestyle changes.
Metabolic Effectors In Weight Management
Metabolic pathways that play a significant role in weight regain or the maintenance of the lost weight can be divided into intrinsic and extrinsic factors. Extrinsic factors span the lifestyle and psychosocial parameters, while intrinsic factors focus on energy balance and functional resistance to weight loss. Both the processes are interconnected through complex metabolic networks. Accordingly, weight loss in individuals with high baseline fat mass progresses to steady maintenance of the lost weight. High-fat concentrations lead to loss of fat weight without stress to the adipocytes or reduction of fat-free mass. Continued weight loss management requires effective regimes spanning both intrinsic and extrinsic factors, i.e., limited energy intake, exercise, and a fat-free composition of the diet, proper sleep, besides genetic variability. The final goal is to prevent weight regain by maintaining minimum cellular stress and accumulation of fat. The primary weight gain and weight regain are different metabolic processes. Hence, preventing weight recidivism requires controlling a set of metabolic indices different from those targeted during initial weight loss. Sustaining weight loss underlies diverse homeostatic metabolic adaptations through the modulation of energy expenditure that improves metabolic efficiency. However, it leads to an increase in the signals for energy intake.
Maintaining Energy Balance Through Fat-free Mass and Hormone Regulation
The percentage of body fat lost during calorie restriction negatively correlates with the rate of weight regain, which depends on the baseline BMR. Thus, higher initial BMR is usually helpful in successful weight maintenance after weight loss.[39] Weight maintenance diets through which fat-free mass is spared are usually less effective in preventing weight regain. Fat-free mass is highly involved in energy expenditure by physical activity. Hence, to increase the possibility of weight maintenance after weight loss, diets rich in protein and low glycemic index are advised together with physical activity. Compared to a low-fat diet, a low glycemic index diet has a more pronounced effect in reducing hunger, minimizing postprandial insulin secretion, and maintaining insulin sensitivity.[40]
Other major regulators of weight maintenance after weight loss are metabolic hormones that modulate the feelings of hunger and satiety, such as leptin, insulin, ghrelin, etc.[41] After a weight-loss period, the reduction in fat mass leads to a decrease in plasma leptin. This drop in the plasma leptin concentration creates a leptin deficiency signal in the brain that subsequently induces a high energy intake response. With 10% body weight loss, a significant deficiency in brain leptin concentration is observed. An experimental observation indicated that injection of leptin in such individuals during the weight maintenance period was associated with a reversal of the deficiency symptoms in the brain areas dedicated to energy intake regulation. Thus, there exists a direct link between leptin and the weight loss process. Leptin concentration changes over time throughout the weight loss regime and subsequently maintaining a healthy weight. Besides leptin, reduction in the concentration of thyroid hormones, triiodothyronine (T3), and thyroxine (T4) also substantiate weight loss. Notably, thyroid hormones are directly correlated to the leptin concentration throughout weight loss and maintenance.[42]
Similarly, a higher baseline concentration of ghrelin hormone is also associated with improved weight loss. In addition, alteration in plasma ghrelin concentration is related to increased satiety. However, unlike leptin, ghrelin doesn’t seem to have a long-term effect on body weight maintenance. Finally, the hypothalamic-pituitary-thyroid axis seems to be the central modulator for weight maintenance through the influence of leptin as well as other regulatory metabolic hormones.[43]
Other metabolic hormones, namely, peptide YY (PYY), gastric inhibitory peptide, GLP1, amylin, pancreatic polypeptide, and cholecystokinin (CCK), are sporadically shown to regulate hunger and satiety signals. The concentrations of hormones PYY and CCK were shown to reflect initial weight loss levels even after 40% weight gain, thus indicating a negative correlation to weight maintenance after weight loss.[44] A good understanding of these hormones in regulating energy intake can help devise therapeutic or preventive regimes for weight regain.
Physiologic and Cellular Regulation of Weight Maintenance
The plasma concentration of metabolites reflects the physiological activities of tissues and cells. Plasma concentration of some metabolites is observed to vary over time during and after the weight loss and maintenance process, indicating metabolic adaptation response.[45] The major metabolites that are shown to undergo a time-dependent change effect are free fatty acids, triglycerides, HDL, cholesterol, β-hydroxybutyrate, and glucose. After weight loss, the generation of negative energy balance alters the plasma concentration of metabolites, which is re-established when energy balance takes a new homeostatic position. Hence, the plasma metabolites concentration may reflect metabolic mechanisms that resist weight modulation. Metabolite concentrations are modulated depending upon the amount of weight lost. Research has indicated that a 10% weight loss may lead to the long-term persistence of concentration change in some metabolites. However, the return effect of the plasma concentration of metabolites such as angiotensin I-converting enzyme (ACE), insulin, and leptin to a threshold level are shown to reflect a possible weight regain.[46]
The correlation of plasma leptin, baseline BMI, and initial fat mass with a risk for weight regain points to an active role of the adipocytes. After losing fat, adipocytes experience cellular stress. The cells become smaller in size upon fat loss affecting the structure-function axis of adipocytes.[47] This is alleviated by adjusting to a new energy balance and renewal of fat and triglyceride storage mechanisms, accompanied by changes in adipokines secretion. The resultant change affirms sufficient fat supply to the adipose tissue. Adipocyte-based energy demands increase high-calorie intake and establish a risk of weight regain.[48]
Adipocytes regulated energy requirement also correlates with a drop in leptin concentrations. Subsequently, many studies have supported that fast initial weight loss results in a more significant amount of lost weight but induces cellular stress and higher reversal. However, a gradual initial weight loss substantiates metabolic adaptability of adipocytes and a greater prospect for long-term weight maintenance.[48]
Issues of Concern
Weight loss regimes usually depend on dietary modulations and calorie restrictions, exercise, and sometimes drug intervention or surgery. However, it is concerning that most people are unable to maintain the lost weight, and many regain a significant part of the lost weight. Notably, there are individual differences observed in weight maintenance. There is no standard effective regime developed thus far, and individual differences are observed in the manifestation of such regimes, and in some patients, it may not be successful. These differences in the positive outcome of weight loss management programs may be due to lifestyle choices, eating habits, and individual metabolic variations, besides not complying with the healthy diet.
Weight lost through calorie restrictions poses a risk of bone mobilization or bone loss. A combination of calorie restriction and exercise does not necessarily prevent or attenuate bone loss. Losing about 5% of body weight raises the risk for fractures, especially in older age individuals. It requires a controlled weight-loss program design to pinpoint mechanisms adapted to support the quality and density of bone sites susceptible to bone loss. Hence, besides the clinical regime of weight loss from the point when it is initiated to achieving a healthy weight, management of lost weight also requires clinical support.
Weight loss through pharmacological and surgical interventions is becoming more appealing. Besides improving an individual's health and emotional status, they effectively reduce the risk factors for metabolic diseases. Nonetheless, they are associated with significant age-specific side effects. Surgical interventions such as sleeve gastrectomy usually lead to swift weight loss but are accompanied by changes in hormones, bone density, and gastrointestinal problems.
Weight regain after weight loss is also a frequent problem encountered in obesity. This tendency is often due to the lack of compliance to exercise or dietary regimes. However, in many cases, it occurs due to physiological mechanisms and not due to high-calorie intake or lack of exercise. Gut hormone secretions may lead to a reduced secretion of anorectic hormones and an enhanced orexigenic hormone affecting metabolic adaptation. This imbalance causes weight to be regained after weight loss has taken place. The BMI-induced metabolic shift may also lead to the weight regain process. Hence, it concerns that many central (metabolic) and peripheral (food craving, hunger sensation, and enjoyment of eating) mechanisms can cause regain of weight.[49][50][51]
Maintaining weight loss after following a specific regime such as calorie restriction, exercise, drug treatment, or surgical intervention always requires a careful assessment at the individual level. This should be followed by meticulous customization of weight management regimes to achieve a potent, sustained and healthy body weight.
Clinical Significance
Metabolism plays a major role in the maintenance of a healthy weight after weight loss. Besides calorie restriction, exercise is a significant metabolism booster. Exercise helps build lean muscle mass and increases the metabolic rate to utilize more energy in maintaining it. Many health conditions are related to metabolic derangements. Specific illnesses such as insulin resistance, thyroid problems, etc., that may affect metabolic function are associated with an inability to maintain a healthy weight. Some medications such as steroids, blood pressure reducers, antidepressants also induce slowing down of metabolism and hence pose risks of weight gain and regain after a healthy weight loss has been achieved.
From a clinical standpoint, metabolic derangements due to genetic predispositions, lifestyle, behavior, and medication or illness may prevent the maintenance of a healthy weight. Hence, regulation and maintenance of healthy metabolism are imperative to overcome unhealthy weight conditions such as obesity and other associated comorbidities. Notably, as much as 5% weight loss may significantly improve the health of an overweight or obese individual besides reducing the risks for cardiovascular disease, diabetes, impairment in liver and kidney function, etc. Additionally, it leads to an overall reduction of fat and an increase in healthy muscle mass.
Weight loss management is clinically recommended to prevent weight regain and affirm normal blood pressure, healthy triglycerides, and cholesterol levels, or reduce the risk for metabolic diseases. Besides a general health index, maintaining a healthy weight has far-reaching benefits. Healthy weight loss reduction causes a general sense of well-being, more energy, reduction in stress levels and better sleep, improved immunity, better mental health, balanced hormones, and an overall enhancement in the quality of social life.
Enhancing Healthcare Team Outcomes
Weight Loss and Metabolic Consequences
Unhealthy weight gain generally occurs through inducing and driving factors that perturb the metabolism, which may vary among individuals. Hence, the practitioners must recognize and evaluate the underlying causes and prescribe a regime for weight loss directed towards the specific causing and contributing factors to obtain desirable results. Furthermore, weight recidivism is observed at a high rate and thus requires a customized regime spanning metabolic effectors to maintain lost weight. This will involve a concerted effort from multidisciplinary staff such as physicians, nutritionists, exercise physiologists, and trainers to recognize the potential causes and target their treatment strategies accordingly. Besides, weight reduction and regeneration of healthy metabolism also depend on lifestyle, including healthy behavioral practices and eating habits. Thorough counseling of patients will warrant better patient outcomes. Weight management becomes more complex when it is a therapeutic pathway for health conditions such as type2 diabetes, cardiovascular diseases, liver or kidney diseases, etc. The outcomes of such therapeutic intervention may depend on a carefully directed approach that prevents adverse side effects. However, to improve therapeutic outcomes, prompt consultation involving an interprofessional group of specialists is recommended.[52][53] [Level 1]
Calorie Restriction
According to the American College of Cardiology/American Heart Association Task Force guidelines, a hypocaloric diet as a lifestyle change has been proposed to induce weight loss and sustained weight management by optimizing energy balance.[15] Calorie restriction is based on reducing average daily caloric intake without malnutrition or lack of essential nutrients. A nutritionist designs a diet regime in consultation with the physicians to understand the patient's metabolic level and identify comorbidities. This requires the involvement of an interprofessional team that includes physicians, nutritionists, and laboratory technologists. Once the physician and laboratory technologist help diagnose the comorbidity or metabolic causes, nutritionists can help devise an effective calorie restriction regime for weight management.[54] [Level 1]
Physical Training and Exercise
Routine moderate to intense physical activities are effective in preventing weight regain. For a successful weight maintenance program, well-directed physical training is recommended. However, it depends on personal behavior, dedication, and an effective exercise plan. Initially, this was only considered a domain for physical trainers; however, it is realized that only exercise could not lead to healthy outcomes. Thus it is crucial to obtain assistance from experts from other fields. A complete health profile of the patient through diagnosis by a physician and laboratory technologist can help a physical trainer in devising exercise regimes and resistance/endurance training to generate metabolic activity towards sustained weight maintenance [Level 1]
Drug and Surgical Intervention
Prescribing a medication, especially for weight loss or management, requires careful understanding of the patient’s lifestyle, behavior, diagnosis of underlying conditions, and if a person is taking any other drug, etc. Hence to derive a good outcome, a physician must incorporate assistance from specialists, pharmacists, lab technologists, and nurses to achieve a better outcome from drug therapy when dietary regimes or physical training has not been successful. This also requires complete information about the dietary and exercise regimes to be obtained by the physician. Hence, an interdisciplinary approach is helpful to achieve successful and sustained therapeutic results.
Bariatric or metabolic surgical interventions are a procedure for treating excessive weight gain and for individuals with weight regain. These operations are also carried out to treat diabetes, high blood pressure, sleep apnea, and high cholesterol. These operations modify the stomach and intestines to treat obesity and comorbid conditions. The operation is intended to constrict the stomach size in addition to bypassing a stretch of the intestine. This changes food intake and absorption of food resulting in less hunger and a feeling of fullness. Surgical intervention poses a risk factor for the patients; hence assistance for interdisciplinary teams constituting surgeons, nurses, pharmacists are mandatory for assessment, post-operative patient care, monitoring, and follow-up. Furthermore, better outcomes can be enhanced by counseling and informing the patients about the goals and objectives of the bariatric surgery a priori.[55][56] [Level 1]
The surgical procedures used for metabolic surgery are:
- Sleeve gastrectomy
- Gastric bypass
- Adjustable gastric band
- Biliopancreatic diversion with duodenal switch
- Single anastomosis duodeno-ileal bypass with sleeve gastrectomy
All these surgical procedures are usually aggressive, and hence reversal is not easy. Reversal may usually result in complications and risks. After a sleeve gastrectomy, the procedure can never be reversed.
Evidence-based Approach
Excessive and unhealthy weight gain generally progresses through inducing and driving factors that perturb the metabolism and vary among individuals. Long-term management of overweight conditions and maintenance of lost weight requires ongoing clinical attention. A weight management regime follows a sequential metabolic adaptation towards establishing sustained homeostasis. An interprofessional staff involving physicians, surgeons, nurses, pharmacists, nutritionists, exercise physiologists, and trainers who can determine the underlying causes and devise regimes can provide a holistic and integrated approach towards weight maintenance.[57][58][51] This will facilitate the best possible outcomes. The basic indices that define metabolic derangements as key culprits for weight regain must be evaluated before determining a therapeutic regime. Hence, the essential role of diagnostic laboratory professionals cannot be undermined.[59]
A collaborative effort in decision making and patient counseling are key elements for a good outcome in weight management to prevent recidivism. The interprofessional care of the patient must follow integrated care management combined with an evidence-based method to planning and evaluating all activities. A thorough understanding of signs and symptoms can lead to implementing a more successful regime and better outcomes.[60] [Level 3]
Metabolic Consequences Of Weight Reduction