Key commented, “Contrary to the current popular views that a diet low in carbohydrates and high in proteins keeps weight down, we found that the lowest weight gain came in people with high intake of carbohydrate and low intake of protein.”
Another study conducted by the Imperial College London published in the American Journal of Clinical Nutrition observed nearly 400,000 adults over five years and concluded “that eating meat was linked with weight gain, even in people taking in the same number of calories.” They found that the strongest link between eating meat and gaining weight was the increased consumption of processed meats such as hot dogs, ham, and bacon. The team also calculated that within a group of people who ate the same amount of calories, those that ate 250 grams more meat a day gained an additional 4.4 pounds/2 kilos over the five years.
It is important to note that this isn’t true of all vegetarians and vegans. For example, if a vegetarian eats only fries and Twizzlers, it’s unlikely that they’d be thin or even very healthy for that matter. The healthiest, thinnest vegans and vegetarians are typically the ones who maintain a diet full of vegetables, fruits, beans, nuts, and soy products because eating lots of fiber-filled foods will fill you up quickly with less calorie and fat intake.
Putting aside the “same calorie intake” studies for a moment, meat does contain hundreds more calories and lots more fat than plant-based foods, which also contributes to weight gain. For example, a 110 gram serving of black beans has 104 calories and 0.3 grams of fat whereas a same sized pork chop serving contains 237 calories and 15.4 grams of fat. A 110 gram serving of steamed broccoli has 38 calories and 0.4 grams of fat when a 110 gram serving of 90% lean beef mince has 199 calories and 11.3 grams of fat. You’d have to eat almost 6 servings of broccoli to consume that many calories, and you’d still only have eaten a fraction of the fat! Anyways, you get the idea. While there are some lean meat choices such as skinless chicken and fish, meat still tends to be more calorie dense than plant-based foods.
To cut even more calories and fat, try going vegan for a day. It seems fairly obvious that not eating animal by-products such as cream, butter, eggs, and cheese leads to more weight loss. Their high calorie and fat content coupled with their lack of much nutritional value means they can be skipped quite easily and replaced with something animal friendly that your body actually needs. Try using soy milk in your coffee, eating fruits and whole grains for breakfast, and spreading hummus on your sandwich!