When it comes to weight loss, protein is king.
From Atkins to Paleo, you’ve no doubt heard that the way to slim down is to cut carbs and up your intake of things like fish, chicken, eggs, legumes, nuts and seeds.
And it’s really not just a nice theory — a huge body of research on the topic suggests that reducing carbohydrates and replacing them with protein can not only help you lose weight, but also help you lower your body fat percentage, which is an important marker for overall health.
One study found that people who lost weight using a high-carbohydrate diet were breaking down about 35% lean tissue and 65% fat. However, on a high-protein diet, lean tissue breakdown dropped to 20%, while fat breakdown increased to 80%. And even when weight loss results are similar, fat loss tends to be higher on low-carb, high-protein diets.
Why is protein so beneficial in weight management?
To begin, protein has greater satiety than either carbohydrates or fat. Eating it makes you feel fuller and satisfied for a longer period of time. By curbing hunger, high-protein meals help you better control your appetite, reduce post-meals cravings, and eventually eat less.
Another way protein impacts weight loss is via thermogenesis, or the amount of energy needed to digest, absorb, and metabolize the nutrients you eat. Because protein has a higher rate of thermogenesis than both carbohydrates or fat, your body uses up more calories trying to digest protein than other foods.
But the most dramatic way in which protein affects metabolism and energy expenditure is through its role in muscle building and maintenance. There is evidence that you need a minimum amount of protein at a meal in order to preserve your lean body mass during weight loss and to achieve a more desirable body composition.
So how much protein do you need?
The exact amount of protein should be determined according to your body weight (or better yet, your lean body weight as estimated through a body composition analysis). However, a good rule of thumb would be to eat at least 30 grams of protein in a meal. This threshold amount has been shown to stimulate muscle building and help maintain lean body mass. Since positive protein balance only lasts about three hours after ingestion, it’s important to eat enough protein throughout the day. This means no skipping meals – eat breakfast, lunch and dinner (with a mid-morning and late afternoon snack in between meals, if you’re hungry).
Eating enough protein becomes even more important during aging, because your ability to use protein efficiently gradually decreases after you turn 40. You might be surprised to hear that a 65-year-old is likely to need more protein than a 16-year-old. Though you may require fewer calories as you age, you need more high-quality, nutrient-dense protein (along with exercise and resistance training) to prevent muscle wasting.
How can you ensure you eat enough protein without exceeding your calorie allowance?
Try to get your protein mostly from very lean protein sources. Aim for foods that contain one gram of fat or less per ounce. Examples of good sources are: whey protein powder, chicken and turkey breast (white meat only, no skin), egg whites, nonfat cheese, nonfat Greek-style yogurt, white tuna (canned in water), fish (such as cod, flounder, haddock, halibut, trout, tilapia, and shellfish,) and very lean selections of turkey bacon, Canadian bacon and luncheon meats.
Also, focus on breakfast first. Studies show that most of us tend to eat almost all of our protein in a single meal: dinner. For most people, breakfast is usually the meal of the day you get the least protein, so make sure to start your day with a positive protein balance.
When you keep your protein intake at an optimal level, you’ll not only start seeing the pounds come off (if you’re not overdoing it carbs, that is), but you’ll probably have more energy, focus, and stamina. Protein is also important for avoiding that dreaded late afternoon slump – so keep a protein-rich stash of snacks at your work desk to keep you from reaching for a quick pick-me-up through sugar or caffeine.
Layman DK. Dietary Guidelines should reflect new understandings about adult protein needs. Nutr Metab (Lond). 2009, 6:12.
Layman DK, Evans E, Baum Jl, et al. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr. 2005; 135(8):1903-1910.
Pandon-Jones D, Westman E, Mattes RD, et al. Protein weight management, and satiety. Am J Clin Nutr. 2008; 87(5):1558S-1561S.