Damian Sendler: Obesity caused by a positive energy balance is a serious health problem. Obesity has been linked to a slew of diseases, including type 2 diabetes, coronary heart disease, and a variety of cancers. As a result, the prevention and treatment of weight gain are critical. The following treatments have been shown to be effective based on current research: lifestyle changes, special diet plans, prescription medications, and bariatric surgery. Each of these options takes into account the patient’s medical history as well as their BMI category and other co-morbidities. Change in behavior and an increase in energy expenditure are essential for all treatment options. Self-monitoring of food intake and physical activity is a powerful tool for weight loss behavior change. Self-monitoring with digital tools has the potential to improve weight management because they increase self-engagement. It is the goal of this narrative review to summarize the current available treatment approaches for obesity, to provide a selective overview of nutrition trends, and to present a scientific viewpoint on various nutrition concepts for weight loss.
Damian Jacob Sendler: Complex, multifactorial, and largely preventable obesity is defined as abnormal or excess fat accumulation [1]. Weight in kilograms divided by height in metres (kg/m2) is currently the most commonly used criterion for determining whether someone is obese. Obesity is defined as a body mass index (BMI) greater than or equal to 30 kg/m2 (Table 1). In addition to the health risks associated with being overweight or obese, the BMI also measures how much weight a person carries around in relation to their height (Table 1). BMI and waist circumference are used in clinical practice and medical guidelines to measure weight status and abdominal obesity because they are simple, objective, and reproducible. However, BMI alone should not be used to diagnose obesity; other anthropometric and clinical parameters should be considered as well. Body composition and adipose tissue depots can be assessed with the aid of instruments (e.g. bioimpedance analysis, Dual Energy X-ray Absorptiometry, and magnetic resonance imaging) that can be time and money consuming.
Dr. Sendler: Type 2 diabetes, hypertension, dyslipidaemia, cardiovascular disease, and a variety of cancers are all directly linked to being overweight or obese [4]. BMI has recently been shown to be a predictor of severe coronavirus disease 2019 (COVID-19) outcomes [5]. An increase in BMI may also decrease quality of life and shorten life expectancy [6,7,8,9].
Long-term imbalances in energy intake and expenditure are the primary causes of obesity [1, 6, 10, 11]. From 1971 to 2000, the average daily energy intake in men increased by 168 kilocalories (kcal)/day and in women by 335 kcal/day, according to the National Health and Nutrition Examination Survey (NHANES). Men can theoretically gain eight kilograms of weight per year, while women can theoretically gain 16 kilograms of weight per year without any active regulation or adaptation of energy balance. Over the past few decades, the amount of energy consumed has decreased. Adults in the United States walked an average of 5k steps per day in 2003, according to Basset and colleagues. For men, it’s a difference of 13,000 steps/day, and for women, it’s a difference of 9000 steps/day. Men and women gain an average of 31 kilograms per year from a decrease in physical activity without any physiological adaptation. Work-related daily energy expenditure has dropped by over 100 kcal/day in adults in The United States. Over the past five decades, there has been a significant increase in the population’s weight. Other contributing factors, such as diet and the surrounding environment, have been discovered in addition to a person’s way of life [15].
There has been an exponential rise in obesity rates over the last half century [3,6,16,17,18] that has reached pandemic proportions worldwide. Using data from 68.5 million people, the Global Burden of Disease study found that 603.7 million adults were obese in 2015 [19]. Obesity rates have doubled in over 70 countries since 1980 and are still rising in the majority of them [19]. It is predicted that 38% of adults in the world are overweight, and another 20% are obese [20] if current trends continue. As a result of the COVID-19 pandemic, people’s eating and exercise habits have shifted, creating an obesity-inducing environment. [21,22] have shown weight trajectories during the COVID-19 lockdown. Overweight and obesity are expected to rise as a result of this new COVID-19 pandemic [23].] [24, 25]. Obesity is on the rise, and in order to combat this public health problem, it is imperative that BMI be monitored and evidence-based interventions be identified, implemented, and evaluated [19].
In order to treat overweight and obesity, it is generally recommended that people adopt a negative energy balance-inducing lifestyle. Nutrition, physical activity, and behavior are the main components of a variety of lifestyles. An energy deficit of 500 kcal a day should be achieved by reducing energy intake and increasing physical activity, along with behavioral change techniques. Over the course of a year, a moderate amount of weight loss can be achieved. Losing weight alters the energy balance, necessitating a change in energy intake and expenditure. Weight loss results in a new energy equilibrium at a lower level because energy balance is dynamic. It can be difficult to stick to a healthy lifestyle intervention for many people who are overweight or obese. As part of a systematic review and meta-analysis, a focus on dietary intervention and social support were found to improve weight loss outcomes [24].
Diet and exercise are important factors in maintaining a healthy energy balance. Weight gain occurs when the amount of energy consumed exceeds the amount of energy expended. [25] The European Food Safety Authority (EFSA) recommends the daily dietary intake for carbohydrates of 45 to 65 percent, 20 to 35 percent fat, and 0.83 g protein/kg body weight [26]. To lose weight, a daily energy deficit of 500 kcal is recommended, and this can be achieved by avoiding high-calorie foods. The amount of energy provided by fat is more than twice as much as that provided by carbohydrates or protein, making it an extremely high-energy macronutrient. Reduced calorie consumption is supported by a reduction in daily fat consumption. Low-fat dairy products like cheese and yogurt, lean meat, and the avoidance of hidden fats can all help to reduce fat consumption.
Many low-carb diets have a carbohydrate intake of about 40% of the total daily intake. A ketogenic diet is a low-carbohydrate diet in which the goal is to eat as few carbohydrates as possible. Epidemiological data showed that a daily amount of carbohydrates of 50 to 55% correlates with the lowest mortality rate. High-carbohydrate and low-carbohydrate diets both raise mortality [29]. Low-carbohydrate diets tend to be lower in plant-based foods, which are known to be beneficial to health. Eight randomized controlled studies found that low-carbohydrate diets are better for lipid metabolism in overweight and obese people than diets with a low fat content [30]. Even though fat consumption as a percentage of total caloric intake has decreased, data from the NHANES show that compensatory overconsumption of sugars has increased total caloric intake (Figure 31). In general, the stone age diet is a low carb diet, but it isn’t defined in any particular way. Meat and protein make up a large part of this diet. Renouncing grain reduces the variety of foods available. The short-term effects of a paleo-conform diet were examined in small studies with methodological limitations. It was determined that 159 participants in four randomized controlled trials (RCTs) comparing the paleolithic diet with any other diet pattern were included in the study. There was no significant difference in anthropometric changes between a palaeolithic-type diet and the Nordic nutrition recommendations after 24 months in the dietary changes of 70 post-menopausal women with obesity, according to the results of a study comparing it to control diets [32].
Over the course of six and a half and a half months, participants in nearly 50 studies were found to lose an equal percentage weight regardless of their macronutrient composition [34]. Similarly, 811 people were randomly assigned to one of four diets, each consisting of a different combination of fat, protein, and carbohydrates, for the purposes of a different investigation (20, 15, and 65 percent ; 20, 25, and 55 percent ; 40, 15, and 45 percent ; 40, 25, and 35 percent , respectively). According to the completers-analysis, there were no significant differences between the groups after two years of intervention. Findings were also consistent between low-fat, low-energy, Mediterranean-style diets and low-carb, non-energy reduced diets. Following two years of intervention, the mean weight loss was 3.3, 4.6, and 5.5 kg, respectively [27]. The average weight loss after a year of intervention was approximately 6 kg (low carb diet) and 5 kg (low fat diet) in a study with 609 adults with BMI between 28 and 40 kg/m2 [35]. Better quality systematic reviews and randomised controlled trials (RCTs) are needed to establish the superiority of low-carbohydrate diets over other energy-reduced diets in terms of weight loss, according to an analysis of systematic reviews [36]. Moderate weight loss can be achieved even with plant-based versions of the Atkins diet or the Mediterranean diet. According to a meta-analysis, a Mediterranean diet that restricts energy intake is linked to moderate weight loss.
Dietary macronutrient composition has no significant effect on weight loss, as the research has shown. In order to lose weight, a negative energy balance is necessary when following a low carb or low fat diet.
Every day, at least one meal is replaced by a high-protein meal replacement. Supplementation with vitamins, minerals, and trace elements as well as the amount of energy in each serving is required for these products to be marketed for weight management purposes. You can get them in the form of shakes, soups, or meal bars, for example. Dietary and behavioral changes, as well as a meal replacement strategy, are popular weight-loss methods. A VLCD, which replaces all of a person’s meals with fewer than 800 calories per day, is one option. Additionally, you can try an extremely low-calorie diet (LCD) that provides more than 800 kcal/day, typically between 1200 and 1600 kcal/day. Total weight loss ranged from 8.9 to 15 kg in people with type 2 diabetes and 7.9 to 21 kg in people without diabetes in a systematic review and meta-analysis on VLCDs, which lasted from four to 52 weeks. The amount of time spent in the study had no effect on the amount of weight lost. A kilo of weight was lost on a weekly basis on average [40]. Another study compared the effects of meal replacements and other weight loss interventions on the weight of overweight and obese adults over the course of a year. Diets that provide less than 800 calories per day and total diet replacement were excluded from this review. Meal replacement diets, on the whole, resulted in greater year-over-year weight loss than control diets or alternative diets [41]. Diabetic remission clinical trial (DiRECT) of 306 patients with type 2 diabetes mellitus found that total diet replacement (825–853 kcal/day formula diet for 3–5 months), followed by food reintroduction (2–8 weeks), and followed by structured support for long-term weight loss maintenance effectively reversed type 2 diabetes. 86% of those who lost more than 15 kg (24%) were off all medications and in remission from type 2 diabetes at the end of the study’s 12-month follow-up period. A 46% one-year remission and 36% two-year remission of type 2 diabetes mellitus were observed in the intervention group [42,43].
Intermittent fasting can be done in a variety of ways. 16:8 is a time-restricted eating strategy in which people eat only for eight hours a day and fast for the other sixteen. The 5:2 diet consists of five days of regular eating, with no special recommendations or restrictions, and two days of fasting with an energy intake of 500 kcal or less. An energy-reduced diet was compared to a 5:2 diet (two days of 600 kcal and five days of ad libitum energy intake per week) by Conley M. et al. There was no difference in weight loss between the two groups after six months of intervention (5.3 kg (5:2) and 5.5 kg (standard). [44] Participants with obesity were enrolled in an RCT that compared the effects of alternate-day fasting and daily caloric restriction on their weight. Alternate day fasting (ADF) and caloric restriction (CR) both result in comparable weight loss after six months (6.0 percent versus 5.3 percent) [45]. The effects of intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes have been examined in a comprehensive review and meta-analysis of randomized controlled trials. Weight loss was similar between the two groups in the eleven studies that were included in this review [46]. Intermittent fasting has similar effects on weight loss and cardiometabolic parameters as a continuous energy restriction [47,48,49]. Over the course of three months, Allaf et al. conducted a Cochrane review and found that people who followed intermittent fasting concepts lost more weight than those who didn’t (evidence from seven studies in 224 people). The difference in weight loss between intermittent fasting and energy-restricted diets is lost if they are compared for longer periods of time (3 to 12 months; 4 studies; 279 people) [50]. Intermittent fasting has a positive effect on weight loss because of the energy restriction, not because of fasting alone [51,52].
The effects of fasting on metabolic regulation and cardiovascular health are also discussed in this article. When it comes to postprandial indices of cardiovascular and metabolic health, gut hormones, and gene expression in subcutaneous adipose tissue, there is no statistically significant difference between daily energy restriction and alternate-day fasting with or without energy restriction [51].
Damian Jacob Markiewicz Sendler: In a small study with eleven overweight participants, early time-restricted fasting (eating between 8am and 2pm) was examined for immediate effects on glucose metabolism and gene expression.. Sugar, glycaemic excursions, and the expression of the stress response gene sirtuin 1 (SIRT1) as well as the autophagy gene microtube associated protein 1 light chain 3 alpha (LC3A) increased in the morning before breakfast in comparison to the control group (eating between 8 a.m. and 8 p.m.). When compared to the gene expression patterns in the evening, this was a significant difference. Time-restricted feeding has been shown to improve cardiometabolic health in men with prediabetes, but this effect was found to be independent of weight loss in the study by Sutton et al. [54]. The metabolic effects of skipping breakfast and dinner were also studied in an RCT, which included 17 healthy individuals of normal weight. When compared to a control group that ate three meals a day, those who skipped breakfast or dinner used more energy. When breakfast was skipped, fat oxidation increased [55]. Breakfast skipping has been linked to a 21% increased risk of developing type 2 diabetes in a prospective cohort study [56].
In recent years, the concept of personalized nutrition has gained traction, particularly among commercial companies that offer genetic testing directly to consumers. The inter-individual variability of metabolic response to standardized meal challenges suggests that personalized diets can successfully modify elevated postprandial blood glucose and its metabolic consequences [57]. This is one of the main drivers for personalized dietary recommendations. Postprandial triglyceride (103%), glucose (68%) and insulin (59%) responses following identical meals were found to be highly variable between individuals in the Personalised Responses to Dietary Composition Trial (PREDICT1). The inter-individual variability can be predicted by a variety of intrinsic and extrinsic factors. Here, the scientific evidence for gene- and microbiome-based dietary recommendations is summarized.
Damian Sendler
Based on an individual’s genetic make-up, gene-based dietary recommendations are made. There are more than a hundred genetic loci that have been linked to anthropometric parameters [58, 59], which supports the idea that even the inter-individual variation in weight loss success indicates a genetic component. Genetic research shows that the FTO gene has the greatest impact on a person’s weight gain. Though the FTO gene has yet to be fully elucidated, studies have shown that the gene inhibits brown adipose tissue formation [60]. Numerous companies provide genotyping and diet or weight loss advice. Additionally, commercial DNA methylation profiling services have begun to appear. In contrast to the lack of scientific evidence that genotypes are associated with weight loss, these commercially available direct-to-consumer tests.
Single nucleotide polymorphisms play a minor role in the variation in weight loss between individuals, according to a recently published pooled analysis of weight loss data [61]. Genotype-based diet recommendations were found to have no effect on weight loss by the Food4Me study. No significant differences in weight, BMI (kg/m2), or waist circumference were observed when genetic testing results were incorporated into nutrition counseling compared to counseling and care that did not incorporate genetic findings [63, 64]. The American Society of Dietetics and Nutrition clearly states that “the use of nutrigenetic testing to provide dietary advice is not ready for routine dietetics practice.” Currently available research does not show that specific dietary recommendations for weight loss are particularly beneficial for people with a defined genetic make-up [65]. There is no evidence that gene–diet interactions are a major determinant of the success of obesity treatment, according to a systematic review on gene–diet interactions [66]. Due to the lack of clinical evidence for gene-based dietary recommendations on weight loss, more human studies are needed in the future. Polygenetic scores, instead of single nucleotide polymorphisms, will be used to characterize humans based on their genetic predisposition. For five diseases (coronary heart disease, atrial fibrillation, type 2 diabetes, inflammatory bowel disease, and breast cancer), Khera AV et al. developed and validated a genome-wide polygenetic score [67]. Further data analysis has yielded a polygenetic predictor for body weight [68].
Damien Sendler: Individuals’ diet, as well as the prevalence of diseases like obesity, have been linked to the microbiota of the gut. These connections suggest that microbiome-based personalized nutrition can help people lose weight [59]. Dietary interventions can have a significant impact on an individual’s microbiome and this change is person-specific, as well as influenced by the individual’s physiological characteristics [69]. Complex interactions may be better understood if the microbiome and other personal factors are integrated together [70]. A VLCD reduced bacterial abundance and restructured the gut microbiome, according to Von Schwarzenberg et al. Mice were given the microbiota after the VLCD and lost weight as a result of the transplantation. This study found that the relationship between diet and the microbiome influences energy metabolism. [71] Dietary intake affects gut microbiota structure regardless of weight loss [72]. Direct and indirect mechanisms for gut microbiome influence are discussed in a literature review. [73] Future human intervention studies will need to take into account the composition of the microbiota as well as the presence or absence of specific microbes and their metabolic activity. For personalized dietary recommendations, some companies use microbiome analysis similar to genetic direct-to-consumer tests. However, there are no scientific studies to support these claims as of now. Current research on the microbiome’s impact on health through diet is insufficient to support dietary recommendations based on the microbiome [74].
Programs that address nutrition, exercise, and behavior are available to help people lose weight more effectively. For the most part, these initiatives take place in a single country and are implemented by health insurances or healthcare providers. Worldwide Weight Loss (WW) is the most widely used weight loss program (formerly Weight Watchers). At 12 and 24 months, an international study found that the WW program resulted in a moderate amount of weight loss. After 12 months, the mean weight change (completers-analysis) was 6.65 kg, and the mean weight loss (completers-analysis) was 4.76 kg after two years. Johnston et al. have also shown that people who use all of the intervention tools (weekly meetings, the WW mobile app, and WW online tools) lose more weight than those who do not use all three methods [77]. In addition to OPTIFAST, another well-known program that provides scientific evidence of efficacy after a year, there is OPTIMIST. OPTIFAST is a 12-month program that begins with three months of complete dietary replacement, followed by nine months of lifestyle recommendations and group sessions led by professionals. At 52 weeks, the OPTIFAST program resulted in 10.5 percent weight loss compared to 5.5 percent weight loss when compared to a food-based diet [78]. Weight maintenance was allowed during this study’s active weight maintenance phase.
Damian Jacob Sendler
Behavioral obesity treatment relies heavily on self-monitoring of food intake and physical activity as a key component of weight loss success [79, 80]. Dietary self-monitoring and the frequency with which it is performed have been shown to be associated with weight loss [81]. In addition, when combined with other self-regulation techniques, such as goal setting and feedback, self-monitoring can have a positive impact on weight loss [82,83,84]. Digital self-monitoring was found to have a higher level of engagement than paper-based self-monitoring.
When it comes to long-term behavior change techniques, the use of digital tools like online tools and applications (apps), tracking technologies, or even internet-based support is becoming increasingly popular. In a randomized controlled trial (RCT), Carter et al. compared the acceptability and feasibility of a smartphone app-based weight management intervention to that of a website and paper diary. According to the findings, the smartphone app group lost an average of 4.6 pounds in six months, compared to 2.9 pounds for those who used a paper diary and 1.3 pounds for those who used a website. Some research suggests that apps for weight loss may improve weight-related outcomes, but the quality of the studies used to support this claim is mixed [87,88]. Villinger and his colleagues conducted a meta-analysis with over 6300 participants to find out whether or not apps can change people’s eating habits and their health outcomes [89]. Health-related data can be collected quickly and cheaply using digital tools like apps, which have the potential to be widely disseminated and scalable [85,90,91]. Even though there are numerous weight loss apps available, they rarely include evidence-based strategies for behavioral change [92,93].
Many drugs are available to treat obesity pharmacologically, including those that reduce hunger, empty the stomach more quickly, increase absorption of nutrients, or increase feelings of fullness. In the last six years, some of these have been approved for commercial use, while others are still in the testing phase. [94,95]. A total of five medications have been given the green light for use in the treatment of obesity by the Food and Drug Administration (FDA) in the United States and Europe (EMA), including orlistat (as well as phentermine/topiramate, naltrexone/bupropion, and liraglutide) [96]. The goal of pharmacotherapy in the treatment of obesity is to improve patient compliance with dietary and lifestyle changes while also countering the physiological changes that occur when a person loses weight.
Behavioural interventions with one anti-obesity medication can lead to greater weight loss than usual care conditions [96]. Over the course of a year, many anti-obesity medications are only able to reduce body weight by 5–10 percent, and weight loss typically lasts only six to eight months [98]. Five weight loss medications (orlistat, lorcaserin, naltrexone-bupropion, phentermine-topiramate, or liraglutide) were compared in a systematic review and network meta-analysis for their effectiveness in weight loss. In total, 28 RCTs with 29,018 patients were included in this review. There was a statistically significant difference between the placebo group and the drug group in terms of the odds of losing 5 percent of body weight after a year. For phentermine-topiramate, topiramate, liraglutide, bupropion, naltrexone, and orlistat, the excess weight loss was 8.8 kg, 5.3 kg, 5.0 kg, and 3.2 kg, respectively.
People who are morbidly obese may benefit from bariatric surgery. Bariatric surgery can be used for a variety of reasons in various countries. Bariatric surgery is generally only available to those who have tried and failed at other weight loss methods in most countries. Food restriction and malabsorption are the two primary mechanisms. By restricting the amount of food one can consume, one can keep the rest of one’s digestive system intact, thus reducing one’s risk of obesity. Bypassing or removing part of the meal results in a loss of calories and nutrients. Because food travels a shorter distance through the gut, fewer kilocalories and nutrients are absorbed. An annual report on all bariatric surgeries submitted to the Global Registry is published by the International Federation for Surgery of Obesity and Metabolic Disorders (IFSO) [100]. From 2014 to 2018, data from 51 countries where documented surgery had taken place was studied and analyzed. Sleeve gastrectomy (46.0%), Roux en Y gastric bypass (38.2%), one anastomosis gastric bypass (7.5%), and gastric banding (5.0%) were the most common surgical procedures [100]. Puzziferry et al. conducted a systematic review that examined 29 clinical studies involving 7971 patients. Gastric bypass was found to be more effective than gastric band weight loss [101]. All current bariatric procedures, according to a meta-analysis and systematic review, are associated with significant weight loss, but one-anastomosis gastric bypass and sleeve gastrectomy still need more long-term data [102]. In particular, patients who adhere better to their pre-surgery visits and behavior changes are more likely to experience greater weight loss following surgery [103]. In any case, the best results are only possible with thorough pre- and postoperative planning [104]. Preoperative evaluation necessitates a number of steps. Psychological readiness for bariatric surgery, professional nutrition assessment, and patient education are all important components of the bariatric surgery preparation process. Modifications to the gastrointestinal tract cause nutritional deficiencies to be a long-term clinical issue in patients [105]. Following bariatric surgery, European Association for Endoscopic Surgery (EAES) clinical practice guidelines recommend postoperative nutritional and behavioral advice [106]. As part of weight management after bariatric surgery, nutrition monitoring is critical for ensuring that patients adhere to healthy eating and supplementation regimens. Additional benefits include preventing weight gain and identifying possible nutritional deficiencies, as well as contributing to the preservation of a healthy lifestyle.
