A new study from Harvard was just published in the New England Journal of Medicine and it wasn’t an obesity study.  It was a study about how people gain weight over time.  Most studies say it’s about diet and lifestyle, but this one goes so far as to say which foods may be the culprits – and which ones could help prevent the “creeping five pounds.”

Visualization is courtesy of TheVisualMD.com

Studying 3 different groups that included over 120,000 people for about twenty years, the researchers found that there wasn’t really massive weight gain at one time.  Rather, each 4-year period delivered just shy of 3½ pounds of weight gain.  That’s less than a pound a year, but over 20 years it adds up. 

Where’d the weight come from?

Here’s where it gets interesting.  Certain foods were “associated” (note that word – I’ll discuss later) with greater weight gain.  Here are the biggest contenders and the amount of weight gain they were “associated” with during a 4-year period:

• Potato chips: (1.69 lb.)
• Potatoes: (1.28 lb.)
• Sugar-sweetened beverages: (1 lb.)
• Unprocessed red meats: (0.95 lb.)
• Processed red meats: (0.93 lb.)

As for lifestyle, having recently stopped smoking was associated with a gain of 5.17 pounds and getting less than 6 hours or more than 8 hours of sleep explained a modest weight gain as well.

Any winners?

Plenty, and this is where we should focus our attention.  Not everyone gained weight over the 20 years.  Some lost weight and there were some common factors that ran through the diets and lifestyle of this crowd, too.  Here are some of the foods featured in the diets of the winners and the amounts of weight they accounted for:

• Yogurt: 0.82 lb.
• Nuts: 0.57 lb.
• Fruits: 0.49 lb
• Whole grains: 0.37 lb.
• Veggies: 0.22 lb.

Biggest influence on weight loss in this group: physical activity.  It explained a loss of 1.76 pounds over each 4-year period.  Bravo to this group for being active as they got older.

The devil is in the details

The study may come from Harvard, but Harvard is not God and the study has flaws that warrant attention. 

Most important: “association” does NOT mean “cause-and-effect.”  The weight gainers ate certain foods.  Doesn’t’ mean that if you eat these foods you’ll gain weight or if you avoid them you’re somehow bullet-proof against weight gain.  Weight gain – even a little at a time – is about excess, no matter where it comes from.  These foods may just be ones that people tend to overeat.  Think about it – chips, potatoes (mostly as French fries, by the way), sugary beverages, all stuff that lends itself to overconsumption.  Eat it occasionally and you’re fine.   As for red meat, a 12-oz. steak is still fine – if you make it two meals and trim visible fat.  Then it’s a nice lean food you can enjoy.  

Eating lots of fries and sugary beverages – or lots of yogurt, nuts and fruits, may just be a marker of a level of attention to weight management.  Think about it.  Someone who is monitoring his/her weight closely may be more likely to avoid lots of fries and soda, and swapping them out for yogurt and fruit.

Above all, it looks like your best bets for preventing long-term weight gain are to stop smoking and keep moving. 

Reference: Mozaffarian D. et al. Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men. N Engl J Med 2011;364:2392-404.

Keith-Thomas Ayoob, EdD, RD, FADA

Follow us on Facebook!