If you’ve been tracking diet trends then you know that refined sugar has a big “x” on its back. Whole grains are “in” and saturated fats are still “out.” Many dietary experts suggest adding more protein to our diet to build and support muscle mass, especially if you exercise, and because it’s filling. A study published in Cell Reports in October 2016 suggests that a high protein diet can support significant weight loss in obese women, but without the expected improvement of insulin sensitivity that normally accompanies weight loss.
Quick primer on proteinWhen your body digests protein, it releases amino acids that are essential for helping build and support muscle tissue. Protein is found in a variety of foods, some healthier than others. Protein-rich foods include: Meats, poultry, fish, milk, and other dairy products, eggs, nuts, seeds, beans and legumes, tofu, whey and soy protein powders. Wheat germ, soba noodles, and certain grains like quinoa also contain significant amounts of protein.** When choosing protein sources, it’s important to emphasize leaner options like low fat milk and cheese, and plant-based proteins.**** Low calorie high protein versus standard low calorie diet**
This randomized controlled study aimed to determine whether adding more protein to one’s diet would nudge weight loss and also improve insulin action. Because insulin resistance is associated with weight gain and obesity, it’s important for a weight loss diet to also improve glucose metabolism and insulin resistance to avoid type 2 diabetes.
Thirty-four participants were recruited for the 28 week study. Most were obese women (BMI greater than 30), ages 50-65, whose weight had been stable for at least six months and who were sedentary (engaged in less than 15 hours of exercise weekly). Participants in the study were divided into three groups: (a) A weight loss (WL) group on a low calorie diet that offered 0.8g protein/kg body weight per day, (b) a weight loss/high protein (WL-HP) group that was given a lower calorie diet with 1.2g protein/kg body weight per day, and (c) a weight maintenance group that would act as a control group. All three groups ate the same amount of carbohydrates and fats. The WL and WL-HP groups were studied before and after the trial.
Weight loss without insulin improvements
Both groups lost about eight to 10 percent of their body weight at the end of the trial (the control group weight and body composition did not change). The WL-HP group also maintained a higher proportion of lean muscle mass (about a pound), but this was countered by the lack of improvement in muscle insulin sensitivity. The researchers noted that increasing the protein content of a diet can have significant impact on weight. But the high protein nature of the diet did not offer any positive benefits in terms of metabolic health where glucose control was concerned. There were no differences between the two groups in terms of intrahepatic triglycerides, abdominal fat, or basal insulin levels.
So it would seem that a “normal protein level” low calorie diet would be preferable, as it would likely support weight loss and some improvement in muscle insulin sensitivity. In order to preserve muscle mass, it might help to have women train with weights a couple to several times a week. Though higher protein in the diet instigates steady weight loss, it may not be worth it if the goal is to avoid type 2 diabetes.
High protein can benefit some
The researchers acknowledged that this was a small study, and it did not address what would happen in a similar subset of men, or individuals who already have type 2 diabetes. It also should be noted that three long-term interventions — the U.S. Diabetes Prevention Program, the Finnish Diabetes Prevention Program, and the Chinese Da Qing Study — all suggest that a slightly higher protein low calorie diet with 20 percent of calories coming from protein might help to induce weight loss and prevent type 2 diabetes while providing satiation and appetite suppression. This type of diet might also help to prevent weight regain.
Other protein studies have mixed results
There have been numerous studies on high protein diets. High protein diets can help to lower blood pressure. High protein diets can also raise the risk of kidney disease. Losing weight with a high protein diet can support better sleep patterns. Though a high protein sourced-from-animal diet may not be good for the general population (due to levels of saturated fat), it may have unique benefits for the elderly.
The different findings in all of these studies suggest that much more research with larger cohort groups is needed to clarify when a high protein diet may be beneficial and when negative outcomes outweigh positive benefits.** Choose best proteins**
If you want to increase your protein, talk to your doctor first. Aim for quality, lean proteins like:
Greek yogurt: 23 grams of protein per 8 ounces (on average)
Low fat, low sodium cottage cheese: 14 grams of protein per 1/2 cup serving
Eggs: 6 grams of protein per large egg
Low fat, 2 percent milk: 8 grams of protein per 1 cup serving
Whey protein powder: 24 grams of protein per scoop (on average)
Ground beef (95 percent lean): 18 grams of protein per 3 ounce serving
Boneless, skinless chicken breast: 24 grams of protein per 3 ounce serving
Halibut and Sockeye salmon: 23 grams of protein per 3 ounce serving
Canned light tuna: 22 grams of protein per 3 ounce serving
Navy beans: 20 grams of protein per one cup serving
Dried lentils: 13 grams of protein per 1/4 cup serving
Edamame: 8 grams of protein per 1/2 cup serving
Green peas: 7 grams of protein per one cup serving
Peanut butter: 8 grams of protein per 2 tablespoon serving (on average)
Wheat germ: 6 grams of protein per 1 ounce serving
Soba noodles: 12 grams of protein per 3 ounce serving (beware of high sodium sauce)
Quinoa: 8 grams of protein per 1 cup serving
Amy Hendel, also known as The HealthGal, is a Physician Assistant, nutritionist and fitness expert. As a health media personality, she's been reporting and blogging on lifestyle issues and health news for over 20 years. Author of The 4 Habits of Healthy Families, her website offers daily health reports, links to her blogs, and a library of lifestyle video segments.