Obesity and overweight are complex chronic metabolic diseases that result from a combination of multiple factors such as genetics, socio-economic factors, psychological factors, endocrine dysfunction and lifestyle choices such as sedentary lifestyle, physical inactivity and energy-dense diets. Overweight and obesity have profound repercussions on health. Indeed, beyond the aesthetic aspect, overweight and obesity are closely associated with abnormal ectopic adipose deposition, increasing the risk of various chronic diseases such as cardiovascular disease, insulin resistance, type 2 diabetes, dyslipidemia, hypertension, fatty liver and certain cancers. WHO global health estimations show that the worldwide prevalence of overweight and obesity has been rising steadily year after year for the past 50 years. In 2022, with almost 8 billion human beings on our planet, around 38% of the earth's population was overweight or obese, representing around 2.6 billion people, of whom 988 million were obese. But following this trend, projections for our near future are even more grim. By 2035, it is estimated that around half of humanity will be overweight or obese... That's 4 billion overweight people, including 2 billion obese. But in the United States, 75% of Americans are already overweight or obese...
The classification of overweight and obesity is based on the body mass index (BMI). The body mass index is determined using a person's height and body mass. And while it gives no indication of body fat content, BMI remains a relevant index for any non-athlete, albeit with certain limitations, even in this case. BMI is considered normal for values between 18.5 and 25 kg/m². Below 18.5, we speak of underweight. Above 25, it's considered overweight, and above 30, obese.
Numerous studies indicate that a loss of 5 to 10% of body mass can contribute to the clinical improvement of metabolic syndrome. Guidelines for the management of obesity recommend interventions via lifestyle changes, drug treatment and bariatric surgery as common approaches to weight loss. Intervening on lifestyle is one of the best strategies for weight loss. Changing eating habits is an essential part of this. Numerous dietary models, such as the Mediterranean diet, the ketogenic diet, intermittent fasting and others, can promote weight loss. Drug treatment complements these behavioral interventions. Drugs such as semaglutide, liraglutide and metformin, originally designed for the treatment of type 2 diabetes, also promote weight loss by suppressing appetite and carbohydrate absorption. In obese adults, for example, semaglutide enables weight loss of 17-18% in 68 weeks. Finally, although bariatric surgery has a proven track record in treating adults with severe obesity (BMI > 35 kg/m²) and complications, many patients are reluctant to opt for this option because of its invasiveness and long-term complications.
Yet, given the rapid rise in the prevalence of overweight and obesity, and the potential health risks these diseases represent, effective intervention strategies are urgently needed. But between changing eating habits and taking medication, which strategy will be the most effective?
To answer this question, Chinese researchers conducted a retrospective study to compare the effects of drug treatment and dietary modification on weight loss in overweight and obese adults. To this end, researchers compared the impact of a low-carbohydrate diet, balanced dietary advice and drug treatment over a 3-month period. A total of 339 overweight or obese people followed a weight-loss protocol. The advantages and disadvantages of the three interventions were presented to the participants, after which they were given the opportunity to voluntarily choose one of these interventions according to their weight loss goals and economic situation. The “Low-carb diet” group comprised 168 people, the “Balanced dietary advice” group 139 and the “Drug treatment” group 32. The three groups were comparable in terms of age, sex, history of obesity, history of psychiatric illness, marriage and duration of overweight or obesity at each follow-up period.
The composition of a low-carbohydrate diet was 20-30% carbohydrate, 40-45% fat and 30-40% protein. Each person was given a detailed, personalized menu specifying the amount of food they were to consume each day. They were asked to keep track of their daily diet by taking photos or using an app. Each month, a dietician made a face-to-face visit to assess adherence and individual motivation.
Those who received balanced dietary advice were offered a macronutrient breakdown such as 50-65% carbohydrate, 20-30% fat and 10-20% protein. Protein came mainly from bean products, nuts, dairy products, poultry, seafood and lean meat. Fats came mainly from unsaturated fatty acids, while saturated fatty acids were reduced. Carbohydrates came mainly from wholegrain cereals.
Drug treatment consisted of semaglutide (1 mg weekly) and/or metformin (500mg, 3 times daily) to control weight and other metabolic indicators. In addition, they were advised to add physical activity to their daily routine (150-300 min/week).
At an initial consultation, weight and other body composition parameters were assessed using bioelectrical impedancemetry (InBody 720, Bio Space). Monthly consultations followed.
The main results of this retrospective study show that the average total percentage weight loss for patients followed for 1, 2 and 3 months was 4.98% (3.04-6.29%), 7.93% (5.42-7.93%) and 10.71% (7.74-13.83%), respectively. Weight loss of 5% or more can improve metabolic markers such as blood pressure, glycemia, glycated hemoglobin (HbA1c), triglyceridemia and cholesterol. This weight loss can also improve associated pathologies such as fatty liver, type 2 diabetes, obstructive sleep apnea and osteoarthritis, and even reduce the risk of certain cancers.
After one month, patients following a low-carbohydrate diet lost more weight than those following balanced dietary advice and drug treatment. After two months, patients on medication lost as much weight as those on a low-carb diet, but more than those on balanced dietary advice. After three months, there were no significant differences in weight loss between the different interventions. One possible reason for the reduced results obtained with the low-carb diet is that, regardless of the type of intervention used, metabolic adaptation, i.e. a reduction in resting energy expenditure, occurs as weight loss progresses. Another reason could be that overweight or obese people tend to have lower levels of lipolysis than normal-weight people. As weight loss progresses, these processes reduce until weight loss slows down.
Numerous studies demonstrate the efficacy of semaglutide and metformin in achieving significant and rapid weight loss. Consequently, in clinical practice, medical doctors often recommend drug treatment for patients with severe obesity or at least one obesity-related comorbidity, rather than dietary therapy, which is more time-consuming and harder to adhere to. Medications can significantly help weight loss by suppressing appetite and/or delaying gastric emptying. These effects may result from a combination of the drug's effects on the hypothalamus and the gastrointestinal tract. In addition, anti-obesity drugs may cause certain gastrointestinal side effects such as nausea, dizziness and diarrhea, leading to a reduction in food intake.
This retrospective study shows that a low-carbohydrate diet is an effective short-term weight-loss strategy. However, after 3 months, its efficacy wanes, and results are comparable to those observed with an intervention involving balanced dietary advice and drug treatment. As always, results should be treated with caution. Adherence to the study was low, with just under 20% of participants tested by the third month.
In addition to the problems associated with reduced basal metabolic rate, adherence to a diet is often the biggest long-term challenge to successful weight loss. So, while radical changes in dietary habits and lifestyle (reducing sedentary activities and increasing physical activity) remain the healthiest solutions for losing weight and improving health in the long term, drug treatment can help clinically and rapidly improve the state of health of overweight and obese people suffering from comorbidity or significant complications. It is therefore important to take into account individual patient characteristics and long-term results when selecting appropriate weight loss strategies.
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