You’ve heard people say, even some nutrition experts, that a calorie is a calorie. They’ll tell you what counts are how MANY calories you eat, irrespective of the nutritional content or quality of those calories. In other words, you could lose weight on an ice cream diet if you watch your portion sizes. However, “calories in, calories out” doesn’t take into account how your body HANDLES those calories and the hormonal response that happens when you eat them. Now, a new study further shows that the type of calorie you eat matters – and if you must overeat, choose foods that are high in protein.
How What You Eat Affects Energy Expenditure
One way the composition of what you eat could impact your weight is by influencing your metabolism. A 2015 study published in the Journal of Clinical Nutrition looked at this issue. Researchers asked 25 participants to increase their energy intake by 40% for a total of 56 days. Some participants ate a diet high in protein while others ate a lower protein, high-fat diet. The amount of dietary protein the participants consumed varied between 5% and 25% of their total intake. To closely monitor the subjects’ metabolic rate, researchers asked them to live in a metabolic chamber. Boy, that must have been fun!
What they found was energy expenditure increased as the quantity of protein the participants consumed went up. In fact, the observed increase in metabolic rate was proportional to how much dietary protein the subjects took in, not the number of calories they consumed. The participants in this study did gain weight, even the ones who consumed the higher protein diet. Of course, it’s hard to avoid weight gain when you increase your calorie intake by 40% for two months, even if you are eating lots of protein. Still, this study shows protein provides a metabolic boost that helps compensate, to some degree, for overeating.
Protein Calories and Weight Gain
Another study found consuming excess calories in the form of protein did NOT lead to weight gain. In this study, resistance-trained participants consumed 800 extra calories daily in the form of protein. They made no other changes to their training schedule or dietary habits with the exception of consuming more protein calories. After 8 weeks, the participants experienced no change in body weight or percent body fat, despite eating an extra 800 calories a day. Keep in mind, other studies show consuming excess calories as protein DOES lead to weight gain. The difference may be that most of these studies were carried out on sedentary individuals who did little or no exercise. If you’re resistance training, you’re putting those protein calories to use building muscle. If you’re not, you’re more likely to store them.
Why Protein Calories Are Different
What makes protein calories unique? When you eat a high-protein meal, you get a greater boost in resting energy expenditure than when you eat fat or carbs. Unlike carbs and fat, protein and amino acids contain nitrogen groups that your body has to work harder to process. It takes more steps, and thus more energy, to break down protein and amino acids than other macronutrients.
Eating protein gives you a small metabolic boost every time you eat it, although you will likely still gain weight if you greatly increase your calorie consumption, even if it is protein, especially if you don’t do resistance training. Still, if you indulge, eating something high in protein will likely do less damage to your body composition.
Better Body Composition?
Other research shows that even if you gain weight when you overconsume protein calories, the composition of that weight gain is more favorable. In one study, participants who ate a diet high in protein stored 45% of the extra calories they consumed as muscle while those who ate a low-protein diet stored more than 90% as body fat. Big difference!
Of course, this doesn’t mean you should start consuming excess calories in the form of protein – it just means you’re less likely to experience an increase in body fat when you overindulge in high-protein foods than when you shovel down a pint of ice cream or a plate of brownies. In the first scenario, you’ll store those calories in a more favorable manner, more as muscle and less as fat, especially if you resistance train.
Other Benefits of High-Protein Snacks
Another advantage of a diet higher in protein is the satiety benefit it offers. A number of studies show people consume fewer total calories when they eat a protein-rich diet. The combination of protein AND fiber is an especially powerful one – a good reason to get a portion of your protein from plant-based sources like beans, lentils, whole grains, and nuts.
Yet another benefit of eating protein and fiber is how it impacts your blood sugar. When you eat protein and fiber-rich foods and snacks, you get a slower rise in blood sugar and your blood sugar stays more stable throughout the day – that means more energy and less hunger.
Make Your Snacks Protein-Rich Ones
Some people eat cleanly at mealtime but get sloppy with their snacks and eat a bag of chips or cookie rather than a protein snack. The chips and cookies will do little to control your appetite. When you need a snack, think protein. Edamame, cottage cheese, Greek yogurt, hard-boiled eggs, a handful of nuts, string cheese, and hummus or almond butter on whole-grain crackers are better-for-you choices. Carry snacks with you so you don’t fall victim to unhealthy snacks on the run.
The Bottom Line
Calories do count, but, based on most research, you’re less likely to gain body fat when you overindulge in high-protein foods than if you had noshed on carby or fatty snacks. Stick with whole foods, as much as possible, and when you do choose protein bars, make sure the ingredient list is short, has less than 6 grams of sugar, and contains no partially hydrogenated oils or high-fructose corn syrup. You have lots of snack options out there. Don’t focus only on the calories, but make sure what you’re eating is nutritious and high in fiber and protein.
References:
Journal of Clinical Nutrition. 101: 496-505, 2015.
Generation Iron. “Overfeeding Protein Does Not Increase Bodyweight”
Obesity Society “Study Suggests the Human Body Cannot be Trained to Maintain a Higher Metabolism”
Today’s Dietitian. Vol. 17 No. 6 P. 22.
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An Unexpected Perk of Eating a High-Protein Diet for Weight Loss
