Fat Foods: Understanding Weight Gain and Loss

Losing weight is never easy, but new research suggests that “fat foods” are part of the problem.

Fat Foods Chart

Discern the good fats from the bad fats with this handy "Fat Foods" chart.

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If you’ve ever tried to diet to lose weight, you know the advice about what to eat changes all the time. (Butter is good! Butter is bad! Butter is back!) But one weight-loss truism has held up for many years: Calories in, calories out. For years, conventional advice has asserted that the most effective way to lose weight is to burn more calories than we consume. Taking that into consideration, what we’ve been hearing lately is truly startling: Maybe weight loss isn’t all about counting calories after all. Recent studies are shedding light on the fact that certain foods cause us to gain weight in ways that aren’t explained by calories alone. Some experts now suggest a better strategy for losing weight is to focus not on eating less overall, but on eating less of certain problem foods.

What Makes Us Gain Weight?

One author who has written extensively on this subject is Gary Taubes, author of the essay “The Science of Obesity: What Do We Really Know About What Makes Us Fat?” (published in the medical journal BMJ in 2013) and the 2011 book Why We Get Fat. Taubes has written in detail about why our current approach to weight loss (particularly eating less) just isn’t working. He says that to figure out how to lose weight, scientific research needs to focus on the specific mechanisms that cause our bodies to start storing more fat.

Interestingly, research suggests that how we gain weight appears to have a lot to do with our hormones, and one hormone in particular—insulin. This is where our specific food choices become relevant. When we eat refined grains, sugar and starchy vegetables such as potatoes, our blood sugar rises quickly, producing higher levels of the hormone insulin—over time excess insulin is associated with weight gain. To lose weight, Taubes says, a major strategy should be eating fewer refined carbohydrates.

More than Food

Another recent article about how various foods can impact weight loss appeared in the Journal of the American Medical Association in June 2014. (The authors, David S. Ludwig and Mark I. Friedman, also wrote about it in a high-profile article for The New York Times called “Always Hungry? Here’s Why.”) The authors support other researchers’ premise that the quality of our food is more important than the quantity: “Attempts to lower body weight without addressing the biological drivers of weight gain, including the quality of the diet, will inevitably fail for most individuals.”

Like the authors of the other studies, these authors attribute our obesity problem to too much insulin from too many refined carbohydrates, especially in processed foods. But that’s not all. They also studied other quality-based drivers of excess weight: our unhealthy balance of fats (most of us need to consume more omega-3s, fewer omega-6s and to eliminate trans fats); our underconsumption of protein and important nutrients; as well as other lifestyle factors, such as lack of sleep and too much stress.

So what can we take from all this information? Obesity and weight loss are complicated issues, and science uncovers new questions faster than it can determine certain answers. But one fairly firm conclusion we can draw is that we should all eat fewer processed foods, especially starchy or sugary ones.

What About Dairy?

You may notice the only dairy product on either food list (“Good Foods, Bad Foods,” at right) is yogurt, on the “best choices” list. Butter was mildly associated with weight gain. Most other dairy products were relatively neutral, including skim and whole milk, as well as cheese.

Good Foods, Bad Foods

One study that gets very specific about foods that are associated with weight loss (or weight gain) appeared in the New England Journal of Medicine in 2011. It comes out of research from the prestigious Nurses’ Health Study and Health Professionals Follow-Up Study affiliated with the Harvard School of Public Health—a set of data that has been collected from tens of thousands of health professionals over the course of decades.

Frank Hu, the lead author of the study, said when it was released: “These findings underscore the importance of making wise food choices in preventing weight gain and obesity. The idea that there are no ‘good’ or ‘bad’ foods is a myth that needs to be debunked.”

So what are these good and bad foods? Here are a few of the specific food results from the study.

Best Choices

• Vegetables (potatoes don’t count
• Whole grains
• Fruits
• Nuts
• Yogurt

Problem Foods

Potatoes: Potatoes came out looking especially bad. All kinds of potatoes were associated with weight gain, but especially potato chips and French fries.

Sugary beverages: The obvious culprit here was soda, but 100 percent fruit juice was also associated with weight gain.

Meat: This includes both unprocessed and processed meats.

Refined grains and sweets: These were also linked to weight gain, although to a lesser extent than most of the foods listed above.

Learn more at The Nutrition Source from Harvard School of Public Health, which has more information on healthy eating coming out of this study and related research, including tips on how to reduce sugar consumption, eat more whole grains and pick the healthiest sources of protein.