High Protein Diet Blocks Health Benefit of Weight Loss

It’s a tough thing, counseling people on how to eat to lose weight.  There are a gazillion weight loss diets out there.  Plant based, low-carb, low-fat, Paleo, Adkins, you name it.  Everyone has an opinion about what diet is best.

Most of the time doctors tell patients some variation of “any road is fine as long as it gets you where you need to go.”  Meaning, whatever diet you can stick to is fine as long as you get the weight off.

Some recently published research calls that into question.  Dr. Bettina Mittendorfer and her colleagues from the Washington University School of Medicine in St. Louis found that the amount of protein people ate while losing weight impacted insulin resistance.

Why do we care about insulin resistance?  Insulin resistance is a major determinant of risk of diabetes.  We know that obese people have a higher risk of diabetes than lean people, and insulin resistance seems to be the reason why.  What’s the link between a high protein diet and insulin resistance?

Dr. Mittendorfer and colleagues found that when people losing weight ate a modest amount of protein (0.8 grams protein per kilogram of body weight per day) they lost weight and their muscle tissue had improvements in sensitivity to insulin.  When people ate a higher amount of protein (1.2 grams protein per kilogram of body weight per day) they lost weight but their muscle tissue had NO improvement in insulin sensitivity.

One of the reasons doctors tell people lose weight is to improve the metabolic problems associated with obesity.  These abnormalities are tied to insulin resistance.  Insulin resistance is part of the metabolic syndrome which includes abdominal obesity, high blood pressure, diabetes (or high fasting blood sugar, often seen before diabetes develops), high triglycerides and low HDL (called “good”) cholesterol.  Having these markers significantly increases your risk of having a heart attack.

We tell people who are obese and have diabetes, high blood pressure and cholesterol abnormalities that they need to lose weight all the time.  We may need to start telling them HOW to lose weight in more detail.  Low-carb diets (which by definition are high in protein and fat) are touted to decrease cholesterol and decrease the risk of heart attacks, but if they don’t improve the metabolic abnormalities of insulin resistance we might need to rethink this advice.

What does this new research mean in practical terms?  Let’s use my body as an example.  I’m 45 years old and weigh about 160 pounds.  Let’s round me down to 70 kilograms.  (Yay!  Instant weight loss, LOL!)  0.8 grams of protein per kilogram of body weight gives me a target of 56 grams of protein per day.  This corresponds to about 15% of my daily calories coming from protein.  1.2 grams of protein per kilogram is 84 grams protein per day, or just over 20% of my calories from protein.

I use myfitnesspal.com (actually I use the app which is awesome) so it’s easy for me to track my protein grams.  Meat has about 6 grams protein per ounce which means that, if I ate meat, 9 oz of meat would be my entire protein allotment for the day at the lower protein target.

If you are someone who eats Paleo or any other low-carb diet in trying to lose or maintain your weight, I would encourage you to take a look at your protein intake.  Track your intake for a week or two to get an idea of where you are.  It is taken as a given that we need to eat a lot of protein in order to maintain muscle while losing weight, but do we really need to?

Dr. Mittendorfer’s subjects lost weight, and both groups lost the same amount of weight.  The lower-protein group lost a little more muscle, amounting to less than a pound of muscle loss difference between the two groups.  However, the higher-protein group had NO improvement in insulin sensitivity which could be interpreted to mean NO improvement in risk of diabetes and heart disease.

This is not a done deal.  It is far from understood exactly how much protein people need, and what are the dangers of a high protein diet.  For instance, Dr. Mittendorfer’s study enrolled only women.  Would the same findings be seen in men?  Would the same findings be seen if people ate only plant protein?  More research is under way and desperately needed to better understand the impact of protein intake on health.  In the meantime, however, these findings are concerning and should make us take a closer look at our dietary protein intake.

Are you trying to lose weight?  Why?  Is it all about how you look?  Or are you trying to lose weight for the health benefits of a leaner body?  If you are more concerned about how healthy you are than about how you look, think carefully about the weight loss diet you choose.  Think carefully about how much protein you’re eating, or you could be working hard to lose weight and not getting all the benefits you seek.

QUESTION: Do you eat low-carb to control your weight?  How much protein do you get per day?  Will this research change how you eat?


4 thoughts on “High Protein Diet Blocks Health Benefit of Weight Loss

    • You’re right, Lee, it’s NOT a lot of protein, that’s why it’s so surprising. This was a very clean study, using the glucose clamp to assess insulin resistance. It is very concerning because many of us (myself included) are used to advising patients to get plenty of protein while losing weight to preserve muscle. And the two links you shared did not specifically address insulin resistance.

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