Why Does Animal Protein Cause Weight Gain?

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The following is an excerpt from Proteinaholic, which was released by HarperOne.

You might be asking yourself how protein can be associated with weight gain when you have always been told to eat protein to lose weight. There are many possible answers to this very complex question. One comprehensive 2009 review considers mounting evidence that the chronic acid intake from high-protein diets may actually cause cellular dysfunction and eventual weight gain (Berkemeyer 2009). While this article is an interesting read (to me, at least), I think the answer is much more simple.

Volumetrics and Calorie Density
You may have heard of a term called “volumetrics.” Barbara Rolls, Ph.D., a nutritionist at Penn State, invented this term to describe a very simple idea: if you eat food with low-calorie density, then you will not gain weight. The idea is that the stomach has stretch receptors that feed back to the brain when our stomachs are full. If you eat food with lots of calories per weight, by the time your stretch receptors alert your brain that you’re full, you have already eaten too many calories. However, if you eat food with a low amount of calories [per weight], you can stuff your face until your stomach tells you that you’re full without overconsuming calories (Rolls 2000; Rolls and Bell 1999; Rolls, Ello-Martin, et al. 2004).

The Fiber Factor
Fruits, vegetables, and beans are high in fiber, which is not absorbed into our bloodstream. So some of the weight of these plant foods does not translate into calories absorbed. Likewise, the fiber holds water and obviously water won’t cause fat gain. So if you eat a giant 280 gram slice of watermelon, due to the fiber and water, you get only 85 calories. A 280 gram piece of chicken delivers almost six times the calories (480). If you could actually consume 280 grams of olive oil (20 tablespoons, in case you’re crazy), you’d take in a whopping 2,380 calories.

This is why I tell my patients they do not need to count calories when they eat a plant-based diet. I don’t care how many apples they eat, or how much kale they consume. I have never seen anybody get fat from broccoli or bananas. One patient didn’t believe me and tried to prove me wrong by eating six apples a day. She still lost weight. Even the most dedicated overeater will become full before eating too many calories.

As an added bonus, the fiber in fruits and vegetables acts as a binder to the sugar they contain. I don’t recommend drinking juices because they remove the fiber from the sugar. When you drink orange juice, the sugar goes into your system real fast. This doesn’t make you fat, but it does make you hungry in an hour or so. Eat an orange, on the other hand, and the fiber turns the sugar into a slow release pill so you don’t experience the same sugar rush. High fiber decreases the glycemic load of the food, and studies have shown that this really does decrease hunger (Lennerz, Alsop, et al. 2013). I believe this is why fiber is so well associated with weight loss. When you look at large studies, people eating the most fruits, veggies, and grains are eating the highest fiber and thereby eating lower calories and losing more weight than meat eaters (Mozaffarian, Hao, et al. 2011).

Plant-Based Diet for Weight Loss
I have been using plant-based diets for weight loss for many years with considerable success. My goal is not to make everybody vegan, but rather to greatly increase the amount of fruits, vegetables, grains, and legumes consumed, while decreasing our usual reliance on [animal] protein. I want my patients to turn their plate around. I tell them to dethrone the meat from its starring role in the center of the plate. I always hear that plant-based diets are hard to do, but it hasn’t been for my patients. It’s not just me; studies have found that vegetarian diets are very well tolerated in clinical settings (Berkow, Barnard, et al. 2010; Thedford and Raj 2011).

A plant-based diet liberates us from counting calories, but it goes further; I tell my patients not to count anything. Years of counting points and carbs, and weighing portions, has made them addicted to measuring. It is a huge relief for them to stop having to starve themselves and worrying about portions. I instruct them to eat the rainbow with a wide variety of fruits and veggies, without limits. If you are hungry, I tell them again and again, have an apple. Enjoy it fully and don’t worry. I provide them with delicious recipes that allow large portions but with low-calorie content. Time and again they tell me how easy it is to eat this way. They gush over how delicious the food is, how they are never hungry, and how they feel fantastic. Remember, my business is helping people lose weight. If they didn’t lose weight, I wouldn’t be successful. Thankfully, this diet is extremely successful, which is why I recommend it.

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About the Author

Headshot of Garth Davis, MD

About the Author

Garth Davis, MD

Dr. Garth Davis is a practicing bariatric surgeon at Houston Methodist in Houston, Texas. He founded the Davis Program at Memorial Hermann, and starred on the hit TLC show Big Medicine. He is certified by the American Board of Surgery and is a fellow of the American College of Surgeons and a fellow of the American Society for Metabolic and Bariatric Surgery. Davis also competes in marathons and Ironman triathlons and is the author of Proteinaholic: How Our Obsession With Meat Is Killing Us and What We Can Do About It. Find him on Facebook and Twitter.
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