The causes of obesity are multifaceted and complex, involving the interaction of multiple factors such as genetics, environment, behavior, and physiological regulatory mechanisms. Recent studies indicate that a single factor is insufficient to explain the epidemic of obesity; rather, the cumulative influence of various aspects leads to excessive accumulation of body fat. The dietary environment of modern society, changes in lifestyle, and genetic susceptibility together constitute key causes of obesity.
From a pathological perspective, the formation of obesity is closely related to energy metabolism imbalance. When the calories consumed over a long period exceed those expended, the surplus energy is stored in the body as fat, ultimately leading to excess weight. This imbalance is not solely determined by individual willpower but is influenced by a combination of genetic predisposition, environmental triggers, and neuroendocrine system regulation. Understanding these causes not only aids in prevention but also provides a basis for personalized treatment plans.
Genes play a fundamental role in the mechanisms of obesity, with hundreds of genetic loci related to weight regulation identified to date. Specific genetic variations may affect appetite regulation, metabolic efficiency, or adipocyte function. For example, the FTO gene has been shown to reduce sensitivity to satiety signals, leading to a tendency for overeating. Family studies indicate that the obesity concordance rate among twins is as high as 40-70%, significantly higher than that of non-relatives, highlighting the importance of genetic foundations.
New findings in epigenetics reveal that environmental stimuli may alter gene expression patterns. Nutritional status or stress exposure during a mother's pregnancy may affect the metabolic regulatory capacity of offspring through mechanisms such as DNA methylation. This intergenerational transmission of genetic effects keeps the obesity risk in certain families elevated over time.
The dietary environment of modern society is considered a major driver of the obesity epidemic. High-calorie, high-sugar processed foods are inexpensive and easily accessible, while whole grains and fresh fruits and vegetables are relatively expensive and require more preparation time. This "nutritional transition" has led to calorie-dense foods becoming the primary source of daily intake, resulting in hidden excess calorie consumption.
Urban living has also changed energy expenditure patterns. Modern workplaces are predominantly sedentary, commuting relies on motorized transport, and home environments heavily depend on electrical appliances, all of which significantly reduce daily activity levels. Studies show that urban residents' daily non-exercise activity thermogenesis (NEAT) is on average 300-500 calories lower than that of rural populations. Environmental designs, such as a lack of safe walking paths and insufficient recreational facilities, also hinder natural physical activity.
Dietary behavior patterns are key factors directly influencing weight. Over-reliance on eating out and fast food habits leads to hidden excess calorie intake. Research indicates that the average calorie content of meals eaten out is 35% higher than that of home-cooked meals, and the frequency of eating out is significantly positively correlated with body mass index (BMI). Disrupted eating rhythms, such as binge eating and nighttime eating, can interfere with the normal secretion of gut hormones, leading to metabolic disorders.
Lack of regular exercise is a significant gap in energy metabolism. The World Health Organization recommends that adults engage in 150 minutes of moderate-intensity exercise per week, but only 30% of the population meets this guideline. Sedentary behavior has become an independent risk factor— even if exercise levels are achieved, sitting for more than 8 hours a day increases obesity risk by 15%. The time spent using modern technology products is linearly related to body fat percentage; for every additional hour of smartphone use, body fat percentage increases by 0.3%.
Metabolic abnormalities can create a vicious cycle. Insulin resistance leads to excessive glucose storage in fat cells, promoting abnormal proliferation of adipose tissue. Chronic stress stimulates cortisol secretion, leading to abdominal fat accumulation. Certain gastrointestinal diseases, such as gut microbiota imbalance, may also affect calorie absorption efficiency, making it easier to store fat under the same dietary conditions.
Medication side effects are often overlooked factors; antipsychotics, steroids, and antidiabetic medications may lead to weight gain by altering metabolic rates or appetite regulation mechanisms. In terms of medical history, women with a history of gestational diabetes have a 60% increased risk of future obesity, indicating that physiological processes may leave metabolic memories. Aging, accompanied by a decrease in muscle mass and basal metabolic rate, also makes weight control more challenging after middle age.
The formation of obesity is the result of the interaction of multiple factors, with genetic foundations providing potential conditions for risk, environmental triggers creating high-calorie exposure, and individual behavioral choices acting as direct triggering factors. These factors often form a vicious cycle: environmental triggers lead to metabolic abnormalities, which in turn weaken the effectiveness of behavioral changes. Therefore, effective prevention strategies must start from systematic environmental improvements, combined with personalized behavioral interventions, to effectively interrupt the multi-layered causes of obesity.
When the body mass index (BMI) exceeds 24, it is recommended to further assess the level of obesity through body composition analysis or body fat percentage measurement. This method can distinguish between excessive body fat and low muscle mass, which is particularly important for those with normal weight but a large waist circumference, known as "hidden obesity," and helps formulate personalized weight loss strategies.
What are common reasons for regaining weight after dieting? How can it be avoided?Dieting often leads to a decrease in basal metabolic rate, making it easy to regain weight once normal eating resumes. It is recommended to adopt a "gradual dietary adjustment method," such as reducing calorie intake by 500 calories per day, along with high-fiber foods to prolong satiety. It is also important to ensure adequate protein intake to maintain muscle mass and stabilize metabolic rate.
How effective is resistance training in improving obesity-related metabolic syndrome?Resistance training (such as weight training) can increase muscle mass, with each additional kilogram of muscle burning an extra 70-200 calories per day. For patients with metabolic syndrome, combining aerobic exercise with resistance training can more effectively reduce blood sugar fluctuations, improve insulin sensitivity, and decrease visceral fat; it is recommended to engage in moderate-intensity training 2-3 times a week.
Under what circumstances should medication or surgical treatment for obesity be considered?When BMI exceeds 30 and is accompanied by complications (such as diabetes or sleep apnea), or when BMI exceeds 35 and non-surgical methods have not been effective, medication or weight loss surgery may be evaluated. Medication treatment should be combined with behavioral therapy, while surgeries such as gastric banding or gastric bypass are suitable for severely obese patients who meet rigorous medical assessments.
How do environmental factors influence the development of obesity in children? What adjustable home strategies are there?Family dietary habits, screen time, and community safety levels are major triggers for childhood obesity. Improvement strategies include having family meals together to reduce eating out, providing fresh fruits and vegetables as the primary snack options at home, and encouraging at least 1 hour of outdoor activity each day. Research shows that children whose parents are involved in meal planning can reduce their annual weight gain rate by over 30%.
%201.svg)
Copyright © 2025 MedFrontiers. All Rights Reserved.
