The subject of a study in the current issue of the New England Journal of Medicine hits may of us close to the heart. And even closer to the belt.
The title: “Changes in Diet and Lifestyle and Long-Term Weight Gain in Women and Men.”
We tend to gain weight as we grow older — a fact that is of great concern to AICR, because carrying excess body fat is a known cause of 7 different cancers, according to our Expert Report and Continuous Update Project (CUP) (pdf).
For years, we’ve been advising Americans to make small everyday changes to their meals: Add more non-starchy vegetables, fruits, whole grains and beans while reducing the amount of animal protein on your plates so the plant foods take up at least 2/3 of the space, while animal foods take up the rest. We call this approach The New American Plate. (Keep this in mind as you read about the NEJM findings below.)
The new NEJM paper tracked the diets and exercise habits of over 120,000 people over the course of 10 years. They analyzed the data to see which specific diet and lifestyle factors were associated with the biggest changes in weight.
First, the good news: The data suggest that eating more vegetables, fruits, whole grains, nuts and yogurt can help keep weight gain in check. Why would this be? The simplest explanation is that people who eat more of these foods eat less of foods that are higher in calories. Perhaps the extra fiber in the plant foods fill them up and keep them from reaching for more; perhaps the “healthy” fat in nuts and the bacterial cultures in yogurt perform a similar function.
Now the bad news. The list of foods that were associated with the most weight gain over time probably won’t come as a surprise: Sugary drinks. Red meat. Processed meat.
The biggest offender? The single dietary/lifestyle factor associated with the most weight gain? Potatoes — whether boiled, fried, baked, or made into chips or fries.
Other studies have reached similar conclusions with regard to the humble spud. Which is one reason our Expert Report doesn’t just say “eat more vegetables” — it specifies “eat more non-starchy vegetables.” In other words: Don’t kid yourself into thinking that bag of chips counts as a daily vegetable portion.
Potatoes (and corn, another starchy vegetable) can be a part of a healthy diet, but if they’re the focus of the diet — if they show up at every meal and nudge aside a wider variety of colorful fruits and vegetables, that’s when nutrition suffers and, according to this study, the pounds can start to add up.
Although press coverage of this study has been quick to seize on its author’s comments that when it comes to losing weight, “All foods are not equal, and just eating in moderation is not enough,” keep in mind that there’s more to this study than a headline like “To Keep off the Pounds: Pass the Nuts, Hold the Chips” suggests. The bottom line remains the same: To lose weight, burn more calories than you take in. What’s intriguing, and what’s being studied by researchers like Dr. Barbara Rolls, is the effect that foods that belong at the center of the New American Plate (non-starchy vegetables, fruits, whole grains, nuts and low-fat dairy products) have on satiety — how they can help curb hunger, and keep us from taking in more calories than our bodies require.