Anti-Obesity Day 2025: Haven’t we all been there where you and a friend eat the exact same meal, but only you seem to put on weight. We often think it’s about our determination to control but doctors have a different view. As per experts, this difference isn’t about willpower. In fact, it’s all about how each body uses and stores energy. Metabolism, hormone levels, muscle mass, gut bacteria and early nutrition all play a role in how identical meals affect people differently.
According to the National Family Health Survey (NFHS-5), nearly one in four Indian adults is obese. However, the numbers vary sharply across States, even where food patterns are similar. Experts say this gap shows that weight gain cannot be explained by diet alone.
“The human body responds to food in its own unique way. Two people may eat the same meal, but their bodies may burn or store that energy very differently,” says Dr. Ashish Gautam, Senior Director and Head of Bariatric and Laparoscopic Surgery at Max Super Speciality Hospital, Saket.
Why metabolism differs from person to person
Metabolism is the amount of energy the body needs to function. People with more muscle mass burn more calories even at rest, while those with higher fat percentage burn less. This difference alone can change how the same meal affects two people differently.
Daily movement also plays a major role. A World Health Organization report states that around half of India’s population does not meet recommended activity levels. Long hours of sitting lower the body’s energy use, increasing the chances of storing calories from the same food.
Dr. Gautam says, “Even small differences in movement, like walking more, standing more, or reducing sitting time, can change how the body uses the same meal.”
How fat placement affects weight gain
Not all body fat behaves the same way. Visceral fat, which surrounds organs in the abdomen, is known to disrupt insulin function. A 2023 assessment by the Indian Council of Medical Research estimated that 35 crore Indian adults have abdominal obesity, making this a growing concern.
When two people eat a carbohydrate-heavy meal, the one with more visceral fat is likely to experience a sharper rise in blood sugar, followed by a stronger insulin release. This leads to more fat storage from the same food.
“Visceral fat is more harmful because it affects how the body handles sugar and how quickly calories get stored,” Dr. Gautam explains.
How hormonal imbalances affect weight gain
Hormones influence hunger, metabolism and fat storage. Insulin, thyroid hormones, cortisol, ghrelin and leptin are among the key hormones involved.
Any imbalance can change how the body reacts to identical meals. High stress increases cortisol, which leads to more abdominal fat. Thyroid disorders slow metabolic activity. Poor sleep disrupts hunger and satiety signals.
“Hormonal changes make identical meals behave differently in different bodies. One person may burn the food quickly, while another may store it faster,” says Dr. Gautam.
Effect of childhood eating habits
Metabolic patterns are shaped early in life. Children who frequently consume packaged snacks, sugary drinks and low-fibre meals often face irregular glucose responses as they grow older.
India has more than 14.4 million children living with obesity, one of the highest numbers globally. Many of these children carry altered metabolic responses into adulthood, even when they begin eating moderate portions.
Dr. Gautam explains, “If eating habits are unhealthy in childhood, the body becomes more likely to store calories later in life.”
Nutrition quality and food access
The quality of food matters as much as the quantity. The State of Food Security and Nutrition in the World Report 2024 shows that 55 per cent of Indians, around 78 crore people cannot afford a healthy diet. Nearly 40 per cent do not have access to nutrient-adequate meals. As a result, many rely on low-cost, ultra-processed foods that are high in calories but low in nutrition.
Two people may consume meals with similar calorie counts, but the one with a long-standing nutrient deficiency may burn energy more slowly, leading to more fat storage.
“The body adjusts when it doesn’t get the nutrients it needs. It becomes more efficient at storing energy, even from simple meals,” Dr. Gautam says.
Gut health and energy absorption
The digestive system contains trillions of bacteria that affect digestion and nutrient absorption. Some bacteria extract more energy from the same portion of food, while others help regulate metabolism.
Gut bacteria are influenced by diet, sleep, medication use, early feeding patterns and stress levels. This means two people can absorb different amounts of energy from the same plate.
Urban lifestyle and sedentary habits
Urban living has reduced natural physical activity for many Indians. Long commutes, desk jobs, screen-heavy routines and reduced outdoor time all lower daily calorie expenditure.
Even if two people eat similarly, their daily activity levels determine whether the calories are burned or stored.
“Sedentary behaviour has become a major driver of weight gain in cities. Even when food habits stay the same, the body’s energy use has reduced sharply,” says Dr. Gautam.
Obesity rates in India have doubled in the last 15 years
According to the World Obesity Federation, obesity rates in India have doubled in the last 15 years and tripled over three decades. This rise has occurred alongside changes in physical activity, food quality and access to nutritious meals.
Experts say this trend shows that weight gain cannot be viewed only through the lens of diet. Two people may consume the same food, but their bodies will not necessarily process it the same way.
“Obesity is influenced by biology, lifestyle and environment. It is not simply about overeating or lack of willpower,” Dr. Gautam says.
