The Main Diet & Lifestyle Factors Causing Weight Gain

“Eat less and exercise more!”  Easy to say – I’ve been urging it for years on this blog – but it’s hard to carry out.  Harvard researchers decided to look into the specific contribution of different factors of diet and lifestyle, to help people overcome their almost ‘inevitable’ annual weight increase of a pound a year, or more.  Their report is published in the New England Journal of Medicine. 

The researchers’ analyses pooled results from 3 databases – the Nurses’ Health Study I and II and the Health Professionals Follow-up Study – to obtain information from 1220,877 men and women.  The participants were healthy and not obese at baseline.  The search was for links between changes in the various factors and weight at 4-yearly intervals, after adjustments for age, baseline body-mass index for each period, and all lifestyle factors simultaneously.

The average annual weight gain was 3.4 lb for each 4-year period, adding up to an average 16.8 lb over 20 years.  The findings for the 3 databases showed associations between lifestyle changes that were strikingly similar.  Among the dietary factors, the chief culprits were potato chips – for each increased daily serving there was 1.69 lb additional weight gain every 4 years.  Some similar associations for other foods: potatoes in general: 1.28 lb, sugary drinks: 1.00 lb, unprocessed red meats: 0.95 lb, processed red meats: 0.93 lb.

Some foods were associated with weight loss.  An increased daily serving of yogurt: -0.82 lb, nuts: -0.57 lb, fruits: -0.49 lb, whole grains: 0.37 lb, and vegetables: -0.22 lb, over 4 years.

Changes in non-diet lifestyle changes were also linked with weight change: increased physical activity: -1.76 lb, alcohol use: 0.41 per drink per day, smoking, new quitters: 5.17 lb, former smokers: 0.14 lb.  Finally, those who slept 6-8 hours a night gained less weight than those who slept more than 8 or less than 6 hours a night. 

Taken individually, changes in one factor would not make much difference.  But a switch to more healthy foods and drinks would clearly be quite effective.  There’s no single one food that’s going to help a person lose weight, and overall calories will still play a role, but a shift to a more healthy diet (as emphasized by the MyPlate introduction) can do the trick – or at least stop the gain.