What foods lead to weight gain over time?

For a while now, I’ve been saying how counting calories doesn’t work and how healthy food choices fill you up without impacting your waistline. A recent study by the Friedman School of Nutrition Science & Policy at Tufts University confirmed many of the things I’ve been saying. In fact, senior author Dariush Mozaffarian, M.D. and dean of the Friedman School, summed it up nicely when he said, “Our study adds to growing new research that counting calories is not the most effective strategy for long-term weight management and prevention.” However, there were a few findings in there that surprised me, and I wanted to share their findings so you can make better food choices in your own life.

Their long-term study followed 120,000 men and women over the course of 16 to 24 years to see how the foods they ate overtime effected their weight. They analyzed what types of protein participants consumed and the glycemic load of the carbs that they ate. They wanted to look at two things:

1. How do the foods interact to effect a patient’s weight.
2. Do some food options naturally lead to other food choices? For example, do people that eat fish also tend to eat more complex carbohydrates with a low glycemic load?

As I mentioned in the article about sugar, foods with a high glycemic load (like rice, table sugar, and processed foods) spike your insulin levels for hours afterwards, causing your body to store any fat you consume and not release any stored body fat. It also causes your appetite to soar again later which leads to overeating. While previous studies looked at glycemic load in the context of diets, this study looked at it in the context of long term weight gain.

The researchers looked at the types of protein and carbs that subjects ate, and they tried to determine if certain protein sources correlated with certain types of carbs. They wanted to determine what choices ultimately resulted in weight loss, weight gain, or a steady weight. While most of the results were of the “no duh” variety, I actually was surprised by one conclusion and I’m not really sure why it worked the way it did.

The not surprising results

1. People that ate red meat tended to eat high glycemic carbohydrates such as white bread and processed foods, which caused weight gain over time. Why this is not surprising: Simple carbs spike insulin which forces the body to quickly store any consumed fat. High insulin also increases appetite, so these people likely ate more before feeling satisfied. In general red meat consumption is typically correlated with other unhealthy habits such as drinking and smoking which is why it gets a bad rap. Red meat in general is fine, but you should eat it with healthier side dishes and trim all visible fat.

2. People that ate red meat with low glycemic carbs like vegetables mitigated the impact to their waistlines, but still experienced minor weight gain over time. Why this is not surprising: As I’ve mentioned before, while saturated fat doesn’t cause heart disease like we once believed, it can make losing weight harder. Your body can mobilize 50% more fat during exercise when your diet is composed primarily of unsaturated fats. It’s simply harder for your body to remove saturated fat from fat cells, so over time, you’ll hold onto more of it. As I mentioned before, keep your red meat lean or focus on grass-fed beef and it will help greatly.

3. People that ate seafood, skinless chicken, yogurt, and nuts tended to lose weight over time. When they ate low glycemic carbs they tended to lose more weight, but when they ate high glycemic carbs, they still tended to lose weight (though not as much) or maintain their normal body weight. Why this is not surprising: These foods are either low in fat in general or contain healthy, unsaturated fats. Even when insulin was high, these foods provided less fat for storage, and what was stored was easier to release later during exercise.

4. People that ate low fat and fat free dairy tended to increase their consumption of high glycemic carbs over time which led to weight gain. Why this is not surprising: Fat is satisfying to our appetites and provides concentrated energy. You can’t remove one source of fuel without your body looking for a replacement. In general, the low-fat craze in our culture has led to a massive increase in sugar consumption, causing our current obesity crisis.

The surprising results

In general, consumption of eggs and dairy products like full fat cheese, whole-milk, and low-fat milk did not cause weight gain or weight loss. Mixing them with high glycemic carbs did cause weight gain, but using them to replace carbs caused weight loss. Why this is surprising: While dairy from grass-fed cows and eggs from flaxseed-fed chickens produce healthy fats which can help with weight loss, the majority of the eggs and dairy consumed in this study came from the standard saturated-fat laden sources. While I understand how fat can satisfy the appetite and ultimately lead to less overall consumption, it should have been harder for people to release this stored fat during exercise. I normally recommend limiting these food choices, but perhaps they are fine to include more often as long as they are not accompanied by high glycemic carbs. That’s not a license to go nuts, but I do think it’s reasonable to include them as part of your healthy eating plan.

Eat right and your body can regulate

In general, their study confirms what I’ve been saying all along. Your body knows how to regulate your intake and limit overeating if you focus on foods that it has evolved to deal with. Your body knows how to process meat, fruits, and vegetables. Eat these things together and there’s no need to count every single calorie. Just eat reasonably and your body will know when to say when. On the other hand, if you eat processed foods not found in nature, you’ll quickly go into fat storage mode and your appetite control mechanisms will be out of whack (that’s the technical term), which leads to overeating.