We all have some lucky friends who can eat whatever they want, even Pizza and seconds of chocolate cake—and they never seem to gain an ounce. And they don’t even exercise. Arrgh!
Those lucky few were probably born with a higher basal metabolic rate (BMR) than the rest of us. Your BMR, also known as your Resting metabolic rate, is the energy your body requires for your heart to pump blood throughout your body, to breathe, to maintain tissues such as muscles, and to regulate temperature. BMR accounts for about 60 to 70% of your energy expenditure. But there are two other parts to the metabolism image: your physical activity or daily exercise, called thermogenesis activityand the thermal effect of food (TEF), that is, the calories used to digest food and convert it into energy.
Research published in 2021 found that our BMR stays relatively constant from ages 20 to 60, and then starts to slow down as we age. So there’s not much you can do to change your BMR (although adding muscle through strength training can help because muscle mass burns more calories than fat).
While our BMR is pretty much a constant, you they can temporarily affect the thermic effect of food metabolism depending on the type of food you eat, as some foods require more calories to be converted to energy than other foods. High-protein foods, for example, have a high thermic effect, meaning they require your body to work harder to digest them, speeding up your metabolism. At the same time, there are foods that don’t fire up that fat-burning furnace and can actually harm your metabolism. And those worst foods to eat if you want a faster metabolism are made up of simple sugars without fiber, like white bread.
How Foods High in Simple Sugars Affect Your Metabolism
The best foods for boost metabolism are the ones that take the longest to digest and keep you satisfied while the The worst foods for your metabolism. They are the ones that are quickly converted into glucose.
The tool you can use to measure how long it takes for a carbohydrate-containing food to be digested and converted to glucose is called the glycemic index. A food that has a high glycemic index takes less time to digest, so it quickly raises the level of glucose in the bloodstream.
These simple carbohydrates, like candy, soda, and sweet desserts, give your body a quick burst of energy because they break down quickly, but then just as quickly, you’ll feel lethargic and hungry. They tend to make you hungry and can lead to overeating, which is why high GI foods are associated with weight gain. On the contrary, complex carbohydrates like whole grains that have a low GI tend to contribute to weight loss because they take longer to digest and require more calories to do so.
The science
A 2010 study in the journal Food and Nutrition Research illustrated the difference by measuring post-meal energy expenditure for six hours after subjects ate either a processed food meal (a processed cheese sandwich on white bread) or a “whole food” sandwich made with cheese cheddar on multigrain bread.
Comparing measures of the two meals, the researchers found that the subjects required significantly more energy to digest the whole-food sandwich than the processed-food sandwich and concluded that the processed ingredients, especially white flour, lowered metabolism in 50%. Another study, this one in The American Journal of Clinical Nutrition found that eating a high-glycemic index diet promoted overeating, increases in body weight and body fat, and larger waist circumference in a sample of 191 Danish women.
White bread is particularly bad for metabolism
“White flour has all the healthier parts of wheat, like fiber and nutrients, eliminated,” says registered dietitian Lisa Moskovitz, RD, CDNthe CEO of New York Nutrition Group. Removing the fiber makes white bread easy and quick to digest, so your metabolism doesn’t have to operate at a higher rate and burn more calories to break it down, she says.
So arguably the worst foods to eat if you want a fast metabolism are simple sugars with no fiber. White bread may be the poster child for those foods that slow down metabolism, with a glycemic index around 75, simply because Americans eat a lot. Foods rank on the GI on a scale of 0 to 100, with pure glucose scoring 100. Some cold cereals rank even higher than white bread at around 81 on the scale. Other high GI foods that slow down your metabolism include granola, white rice, spaghetti, cookies, cakes, soda—just about anything that’s refined and highly processed.
Put off
It’s hard to increase your resting metabolic rate, but in the short term, you can raise your metabolism to burn fat by exercising more, especially high-intensity effort divided into short intervals.
An even easier way is to avoid the worst foods for your metabolism and choose the best ones:protein rich foods (lean meats, fish, and Greek yogurt) and fiber such as beans and legumes, fruits and vegetables, and whole grains.
Get fiber with these 17 delicious recipes with a simple can of beans.
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jeff csatari
Jeff Csatari, a contributing writer for Eat This, Not That!, is responsible for editing books and magazines for Galvanized Media and advising journalism students through the Zinczenko Center for New Media at Moravian University in Bethlehem, Pennsylvania. read more
