We'll bet that, like a lot of guys, you count yourself among the Fred Flintstones of the world: a carnivorous caveman who'd rather gnaw on a T-bone than spear lettuce leaves. Vegetarianism is foreign to you—unappealing and nonsensical for your muscle-building aspirations.

But guess what? You can build just as much lean muscle on plants. And you won't starve either: Vegetarian staples like beans and peas are more filling than meat.

And if you're trying to trim up your physique, there's an even better reason to go vegetarian: People who eat a plant-based diet lose weight more effectively than omnivores on a low-calorie diet. More specifically, you can rev up your metabolism by melting away "muscle fat," according to new research published in the Journal of the American College of Nutrition.

In the study, 74 men and women with type-2 diabetes were randomly assigned to follow a vegetarian diet or a typical anti-diabetic diet. The vegetarian diet comprised veggies, healthy carbs in the form of grains and legumes, fruits, nuts, and animal products limited to just one portion of low-fat yogurt every day. Dieters got about 60% of energy from carbs, 15% from protein, and 25% from fat. The diabetic dieters stuck to the European Association for the Study of Diabetes guidelines, getting 50% of their daily calories from carbs, 20% from protein, and less than 30% from fat. They focused on foods like beans; dark, leafy vegetables; sweet potatoes; berries; fatty fish; and whole grains. All men and women restricted their diets by 500 calories per day.

For the first 12 weeks, participants were asked not to alter their current exercise regimens. In the next 12 weeks (weeks 13-24), they were asked to do aerobic exercise. Each participant was given a personalized program based on their workout history, though all exercised at 60% of their maximal heart rate twice a week for one hour, as well as once a week at home or in the gym.

At zero, three, and six months, the participants' body fat measurements were tested using an MRI. The researchers studied adipose (fat-storage) tissue in the subjects' thighs to see how the two diets influenced different types of fat: subcutaneous, subfascial, and intramuscular—that's fat found under the skin, on the surface of muscles, and inside muscles, respectively.

The findings: The vegetarian diet was nearly twice as effective for reducing bodyweight compared to the conventional anti-diabetic diet. Vegetarian dieters lost an average of 13.7lbs, compared to 7.1lbs for the conventional dieters.

And while both diets reducted subcutaneous fat right under the skin, the vegetarian diet zapped more intramuscular fat, and was the only diet capable of reducing subfascial fat on the muscle.

For those with type-2 diabetes, this is a crucial finding, since muscle fat can exacerbate insulin resistance. Cutting muscle fat means boosting glucose metabolism, as well as amplifying muscular strength and mobility, researchers say. This is stellar news for men and women who don't have type-2 diabetes hoping to lose weight, too.

"Vegetarian diets proved to be the most effective diets for weight loss," leady study author Hana Kahleová, M.D., Ph.D., said in a press release. "However, we also showed that a vegetarian diet is much more effective at reducing muscle fat, thus improving metabolism. This finding is important for people who are trying to lose weight, including those suffering from metabolic syndrome and/or type-2 diabetes. But it is also relevant to anyone who takes their weight management seriously, and wants to stay lean and healthy."