The increasing prevalence of obesity in many countries has led to its classification as a pandemic. Despite increased awareness and education about obesity, nutrition, and exercise, weight gain continues. A paradigm shift is needed to address this issue effectively. Traditionally, obesity was viewed as a result of overeating or under-exercising, leading to calorie counting and public health messages emphasizing balance. However, this paradigm has changed with a better understanding of energy balance, fat balance, and nutrient partitioning. The fat balance equation, which considers the rate of change of fat stores, is more dynamic and reflects energy balance under normal conditions. This approach does not require metabolic abnormalities or genetic mutations to explain weight gain, suggesting that differences in body fat are normal physiological variations. An ecological model proposes that obesity is a normal response to an abnormal environment, rather than a personal disorder. This model considers biological, behavioural, and environmental influences on body fat. It suggests that obesity is not just a personal issue but a public health problem requiring a collaborative strategy involving multiple sectors. The ecological model is similar to the classical epidemiological triad used in controlling other epidemics. Current strategies are not containing the obesity pandemic. A shift is needed away from the traditional view of obesity as a personal disorder. An ecological approach sees obesity as a normal response to an abnormal environment. This approach requires a collaborative strategy involving multiple sectors. The ecological model uses total energy as a mediator, with fat energy being interchangeable for most conditions. Dietary fat is a key determinant of total energy intake, and total energy expenditure is a major determinant of fat oxidation. Energy intake and expenditure are influenced by various factors, including physical activity. Vigorous exercise may not be as effective for fat oxidation in unfit individuals. Population-level benefits are more likely from modest increases in low to moderate intensity activity than from high intensity exercise. Physiological adjustments, such as changes in appetite and metabolism, help minimize weight fluctuations. These adjustments are more vigorous in response to weight loss than weight gain. Biological factors, including age, sex, hormones, and genetics, influence body fat levels. However, these factors do not explain the large population increases in obesity. Behavioural factors, such as "sloth" and "gluttony," are complex and influenced by psychological factors. Environmental factors, both macro and micro, significantly influence food intake and physical activity. The macro-environment determines obesity prevalence, while the micro-environment, along with biological and behavioural factors, determines individual obesity. The ecological model resembles the epidemiological triad, which has been effective in controlling other epidemics. Recent advances in obesity research may impact individual treatment, but there is a major deficiency in research on the obesogenic environment. Without a supportive environment, treatment programmes are likely to be ineffective. The model suggests that the increasing prevalence of obesity is due to an increasingly obesogenic environment rather than individual pathology. A paradigm shift to understanding obesity as "normal physiology within a pathological environment" is needed for a widerThe increasing prevalence of obesity in many countries has led to its classification as a pandemic. Despite increased awareness and education about obesity, nutrition, and exercise, weight gain continues. A paradigm shift is needed to address this issue effectively. Traditionally, obesity was viewed as a result of overeating or under-exercising, leading to calorie counting and public health messages emphasizing balance. However, this paradigm has changed with a better understanding of energy balance, fat balance, and nutrient partitioning. The fat balance equation, which considers the rate of change of fat stores, is more dynamic and reflects energy balance under normal conditions. This approach does not require metabolic abnormalities or genetic mutations to explain weight gain, suggesting that differences in body fat are normal physiological variations. An ecological model proposes that obesity is a normal response to an abnormal environment, rather than a personal disorder. This model considers biological, behavioural, and environmental influences on body fat. It suggests that obesity is not just a personal issue but a public health problem requiring a collaborative strategy involving multiple sectors. The ecological model is similar to the classical epidemiological triad used in controlling other epidemics. Current strategies are not containing the obesity pandemic. A shift is needed away from the traditional view of obesity as a personal disorder. An ecological approach sees obesity as a normal response to an abnormal environment. This approach requires a collaborative strategy involving multiple sectors. The ecological model uses total energy as a mediator, with fat energy being interchangeable for most conditions. Dietary fat is a key determinant of total energy intake, and total energy expenditure is a major determinant of fat oxidation. Energy intake and expenditure are influenced by various factors, including physical activity. Vigorous exercise may not be as effective for fat oxidation in unfit individuals. Population-level benefits are more likely from modest increases in low to moderate intensity activity than from high intensity exercise. Physiological adjustments, such as changes in appetite and metabolism, help minimize weight fluctuations. These adjustments are more vigorous in response to weight loss than weight gain. Biological factors, including age, sex, hormones, and genetics, influence body fat levels. However, these factors do not explain the large population increases in obesity. Behavioural factors, such as "sloth" and "gluttony," are complex and influenced by psychological factors. Environmental factors, both macro and micro, significantly influence food intake and physical activity. The macro-environment determines obesity prevalence, while the micro-environment, along with biological and behavioural factors, determines individual obesity. The ecological model resembles the epidemiological triad, which has been effective in controlling other epidemics. Recent advances in obesity research may impact individual treatment, but there is a major deficiency in research on the obesogenic environment. Without a supportive environment, treatment programmes are likely to be ineffective. The model suggests that the increasing prevalence of obesity is due to an increasingly obesogenic environment rather than individual pathology. A paradigm shift to understanding obesity as "normal physiology within a pathological environment" is needed for a wider