Diet Plus Exercise Best for Lasting Weight Loss, Finds ICMR-NIN Review

A combination of healthy eating and regular physical activity is the most effective non-drug approach for sustained weight loss and improved metabolic health in adults who are overweight or obese, according to a major review by the ICMR-National Institute of Nutrition (NIN).

The findings, published in the international journal Obesity Pillars, rest on an umbrella review of evidence from 112 systematic reviews and meta-analyses. These covered 2,332 randomised controlled trials and more than 5.07 lakh participant observations drawn from over 50 countries.

Led by ICMR-NIN scientists Mahesh Kumar Mummadi and Samarasimha Reddy, the review compared dietary interventions, physical activity, lifestyle changes and combined approaches for weight management and cardiometabolic health.

All major non-pharmacological interventions produced statistically significant but generally modest reductions in body weight and Body Mass Index. The diet-plus-activity combination, however, gave the most durable results, with participants losing an average of 3.68 kg beyond 12 months relative to control groups.

Low-calorie diets were the most effective option for short-term weight loss, yielding an average reduction of 2.64 kg within the first three months. Physical activity on its own led to smaller reductions in body weight, though its benefits grew with longer follow-up. Lifestyle interventions such as behavioural counselling, goal-setting, self-monitoring and health education also showed positive outcomes that improved over time.

The review also tracked metabolic health. The diet-and-activity combination produced the greatest gains in blood sugar control, lowering fasting blood glucose levels and insulin resistance after 12 months. Physical activity was the most effective strategy for reducing blood pressure, cutting systolic blood pressure by about 6.1 mmHg between six and 12 months. Intermittent fasting recorded the largest short-term drop in diastolic blood pressure and supported weight loss for up to a year, but these benefits did not persist beyond 12 months.

ICMR-NIN director Bharati Kulkarni said the results underline the value of an integrated approach to obesity. Healthy dietary practices, regular physical activity and behavioural support each have a role, but their combination can offer broader and more sustained benefits, she said. This matters particularly for India, where scalable and sustainable approaches are needed to address the growing burden of overweight, obesity and related non-communicable diseases.

Mummadi noted that while the review drew on evidence from more than 50 countries, most studies came from high-income and upper-middle-income nations. India and other lower-middle-income countries remained under-represented, pointing to the need for more locally relevant research.