Too much of any food can lead to weight gain. The ones that make you fat most quickly are, predictably, those with lots of sugar, fats and refined grains. These foods provide easily digested and processed calories with minimal nutrition content. In an effort to identify the lifestyle habits most likely to cause weight gain, Harvard University researchers reviewed the habits and diets of more than 100,000 non-obese people to determine the choices that cause weight gain over time. The study, which was published in a 2011 issue of The New England Journal of Medicine, found that a handful of foods were tightly linked to weight gain.
Refined Starchy Foods Promote Weight Gain
Potatoes, especially the processed versions, such as potato chips, french fries, hash browns and mashed varieties, are among the most likely foods to contribute to weight gain, especially when eaten in excess.
Other refined starches, such as white bread, pasta and crackers, are also among the foods that will easily pack on pounds. These foods have little fiber to slow digestion, so they convert to glucose almost immediately and spike your blood sugar, which raises your insulin levels. Insulin allows for the quick delivery of glucose to your fat cells. If you keep your insulin levels high by eating an abundance of starches, the insulin makes it hard for the fat cells to release that energy for fuel. You keep storing fat, but never efficiently burn it.
Sugary Foods Add Extra Fat
Desserts and sugary treats -- candy, ice cream, pastries, muffins, cakes and cookies -- also correlate with fast weight gain, as demonstrated the Harvard study. They have the same effect on blood sugar and insulin as starches.
Sugary sweetened drinks are another product associated with dramatic weight gain. A 2009 study published in the Journal of Clinical Investigation measured fat gain after 10 weeks of consuming 25 percent of calories from fructose-sweetened beverages or glucose-sweetened beverages. Researchers found significant fat increases in both groups. The fructose-sweetened beverage drinkers specifically experienced the most belly fat gain. Fructose, as in high-fructose corn syrup, is a common sweetener in sodas, fruit punches and some energy drinks.
Red and Processed Meat and Body Weight
Red meat, as well as processed meat such as hot dogs and sausage, also correlates with weight gain, showed the Harvard research. An earlier study published in a 2010 issue of the American Journal of Clinical Nutrition showed red meat consumption correlated with weight gain in overweight and normal weight subjects over a five-year span.
Red meat and processed meat often contain large amounts of saturated fat, too much of which can pose a health risk in terms of heart disease, cholesterol levels and high blood pressure. A 2014 study published in Diabetes showed that participants who overate saturated fat gained notable belly fat in seven weeks, compared to participants who overate polyunsaturated fats. Those who consumed the healthy fats found in nuts, olive oil and avocado gained similar weight, but more in the form of lean muscle tissue.
Foods That Discourage Fat Gain
If you're trying to keep weight gain at bay, eat more vegetables, nuts, fruits and whole grains. These foods were less likely to cause weight gain according to the Harvard study. Dairy also did not lead to fat accumulation.
Moderating portions also keeps your body at a healthy weight. Enjoy a treat now and then, but nightly desserts, soda and processed snacks are a recipe for an unhealthy body. Choose low-calorie, nutrient-rich options to satisfy the munchies but keep from packing on fat. Air-popped popcorn, fresh fruit and low-fat yogurt are options.