Recent National Family Health Surveys (NFHS) revealed how obesity levels have rapidly risen, in both adults and children. According to NFHS -5 (2019-20), the prevalence of obesity increased to 22.9% among males aged 18-69 years from 18.9 % in NFHS-4 (2015–16). Among women of the same age, obesity levels rose from 20.6% to 24%. The percentage of overweight children increased from 2.1% to 3.4%. The Prime Minister’s recent call to combat obesity is a clear signal that public policy has now begun to recognise and respond to the threat an obesity-surge poses to India’s health and economic development.

Biomedical, epidemiological and clinical research in the past three decades has provided greater clarity on the nature and consequences of what has loosely been called as obesity on the basis of an imperfect index which measured a weight-by-height ratio. The Body Mass Index (BMI) has recently faced criticism because it does not differentiate between weights contributed by the body’s fat, muscle, bones and fluids. Further, the pattern of fat distribution also matters. Abdominal fat (visceral adiposity) was noted to be far more inflammatory and pathogenic in causing diabetes, heart disease and cancers than overall fat content in the body. A waist-to-height ratio (WHtR) of more than 0.5 spells trouble.

Visceral adiposity is more common among Indians than general obesity. For that reason, Indians develop obesity-related diseases like diabetes and cardiovascular diseases even with BMI values classified as normal. Since the risks associated with BMI and WHtR rise progressively with increasing values, personal practices and public policies in India must aim to keep both of them well within the normal range, while avoiding the risk of undernutrition. Promotion of healthy diets will benefit everyone in the population, not just the overtly obese.

The ideal diet to consume would be predominantly plant-based, with plenty of fruit and vegetables, nuts and seeds. Fibre-rich foods not only reduce the scale and speed of sugar and fat absorption but also help the growth of friendly gut bacteria (microbiome) which counter obesity and prevent cardio-metabolic diseases. For non-vegetarians, fish is preferable to fowl and fowl to flesh, while maintaining a predominantly plant-based diet. Ultra-processed foods, which are loaded with sugar, salt, unhealthy trans fats or saturated fats, are best avoided as also sugar sweetened beverages. Water is the healthiest drink.

Physical activity reduces body fat, while increasing insulin sensitivity of skeletal muscles and preventing diabetes. Dynamic exercises are good for reducing overall body fat. Weight bearing or resistance exercises are good for reducing abdominal fat. Since smoking increases abdominal fat, tobacco consumption should be avoided.

For healthy behaviours to become natural, easy to adopt and affordable choices, we need to create a conducive environment through public policy measures and settings-based approaches for health promotion. Food and agricultural policies must promote crop diversity which can enable dietary diversity. They must be geared to promote greater production, less processing, and affordable pricing of healthier food products. Fibre-rich, low glycemic foods like millets are preferable to starchy cereals. Recent policies promoting the cultivation and consumption of millets are helpful.

Since ultra-processed foods (UPF) and sugar-sweetened soft drinks induce both general and visceral obesity, public policy instruments must discourage their promotion and consumption. Regulatory measures must include restrictions on sugar, salt and fat content of manufactured food products, front of pack warning labels which clearly caution consumers of high levels of any of these, ban on their promotion through celebrity advertising or misleading health claims, and stoppage of sale in school and college canteens. Fiscal measures should encompass higher taxes on UPF and subsidies for healthier crops and food products. Safe pedestrian paths, protected cycling lanes, and green spaces for community recreation will encourage physical activity.

Apart from promoting health and nutrition literacy through mass media, settings-based health promotion programmes must be scaled up in schools, colleges and worksites. These must combine a healthy food environment with active encouragement of physical activity. Whether for supply to schools, anganwadis, police, armed forces, prisons or other government-run institutions, wherever public money is being spent on food, healthier diets can be promoted by the Union and state governments.

K Srinath Reddy is distinguished professor of public health at the Public Health Foundation of India. The views expressed are personal