So, You Went Vegan. Here's Why You're Not Losing Weight
Vegan diets cause weight loss very predictably. In a huge study of Seventh-day Adventists1, those who had adopted a vegan diet weighed 30 pounds less than meat eaters, on average. In fact, essentially every research study shows the same thing2: Vegan diets cause big-time weight loss.
But what if it is not working for you? That can happen. In my clinic, we use vegan diets for people with diabetes, cholesterol problems, menstrual cramps, migraines, and many other problems. For perhaps nine out of 10 participants, weight loss is a given. For that other one in 10, the problem is usually easy to spot.
Let's look at how a vegan diet works, how things sometimes get off track, and how to fix it (I explore more of these topics in my new book, The Vegan Starter Kit).
A vegan diet, by definition, is all plants all the time. Whether it is seared oyster mushrooms and artichoke hearts over capellini, a bean burrito with jalapeños and pico de gallo, or cucumber sushi with a seaweed salad, everything comes from plants. In their natural state, plants are loaded with fiber, and fiber fills you up with essentially no caloric intake. In contrast, meat, dairy products, and eggs have a big zero in the fiber column. So if you replace meat chili with bean chili or you top your spaghetti with arrabiatta sauce instead of meat sauce, your fiber intake increases. And fiber fills you up, satisfying your appetite before you've eaten too much. A vegan diet also means no animal fat, of course. That is important, because there are 9 calories in every fat gram. Contrast that with carbohydrates, which have only 4. So with that animal fat off your plate, a huge source of unnecessary calories is gone.
When there is plenty of fiber on your plate and very little fat, you get satiated far more quickly. You will swear you are eating the same amount of food, but in fact you are eating less, and you'll see the difference on the scale.
There's more: A vegan diet increases your metabolism. In a study of 64 overweight postmenopausal women3, a vegan diet increased their after-meal metabolism by 16 percent. The effect lasted about three hours after each meal. Here's why: If you were to eat a chicken salad sandwich with mayo, its fat passes into your cells. As it does so, it interferes with your mitochondria—the microscopic "burners" that are trying to burn calories inside each cell. Getting rid of that fat allows your mitochondria to recover, so they can burn calories faster. This has been shown dramatically in research studies. At Pennington Biomedical Research Center in Baton Rouge, Louisiana, researchers put volunteers on a high-fat diet. Within just five days, their mitochondria had slowed down significantly4.
A low-fat vegan diet is just the opposite. The animal fat is gone, and your metabolism can recover. That is why you get a significantly better "burn" after each meal.
So, with all that going for you, what could get in the way?
Here are the questions to ask:
1. Do you actually need to lose weight?
Some people worry about their weight even when they are already in the healthy weight range. Check your body mass index (BMI) using any of the handy BMI calculators you will find online. Just plug in your height and weight. A vegan diet helps eliminate body fat, and if you do not have much body fat, you will not lose much weight.
2. Are you actually following a vegan diet?
If your answer is "Oh, yes, I'd say I'm 90 percent vegan," that extra bit of cheese that lingers on your plate draws 70 percent of its calories from waistline-padding, cholesterol-raising fat. Ditto for that bit of wild-caught salmon. Typical salmon species are 40 to 50 percent fat. And every fat gram packs 9 calories you do not want.
3. What about oils?
Nearly all foods from plant sources are very low in fat. Vegetables, fruits, grains, and beans have only traces of natural fats. But there are a couple of exceptions—nuts and avocados are high in fat. Yes, it's a more healthful fat, compared with the fat in cheese and meat, but all fats—good fat, bad fat, everything—have 9 calories in every gram.
So if you are having trouble losing weight, chuck out the nuts, nut butters, and guacamole. And be especially vigilant about added oils. The oils used in frying (e.g., potato chips and french fries) and salad dressings add unwanted calories, as do the fats added incidentally to a great many packaged foods. The worst of the lot are coconut and palm oils, which are not only loaded with calories but are also high in cholesterol-raising saturated fat. If you want to power up your weight loss, read package labels, and skip those products that have more than 3 grams of fat per serving.
A quick word about exercise: Exercise is not a huge calorie burner. Your body is just very efficient in its movements, not using up a lot of body fat as you move along. You can see this for yourself. Go to the gym, hop on a treadmill, and run flat out for a mile. Then wipe your sweaty brow and push the little button that shows how many calories you have burned. It turns out to be about a hundred. Not very impressive. A 2-ounce serving of cheese on a pizza slice has more calories than that (about 140). Even so, exercise helps. First, it's hard to eat ice cream while you run. It gets you out of the kitchen and makes you feel great without any added calories at all.
So, if a vegan diet has not yet clicked for you, you will want to:
- Check your BMI to see if you really do need to lose weight.
- Do it 100 percent vegan.
- Eliminate added oils and oily foods.
- Take a trip to the park instead of the refrigerator.
Neal D. Barnard, M.D., FACC, is a Washington, D.C.-based physician, clinical researcher, and author. He received his medical degree from the George Washington University School of Medicine and Health Sciences, where he is now an adjunct associate professor.
In 1985, Barnard established the Physicians Committee for Responsible Medicine to promote preventive medicine, conduct clinical research, and advocate for higher ethical standards in research. The Physicians Committee also provides direct medical care through its subsidiary, Barnard Medical Center. He works with patients with diabetes, obesity, and other chronic conditions in clinical research studies aiming to improve the prevention and treatment of these health problems.
Barnard’s articles have appeared in the Journal of the American Medical Association, the American Journal of Clinical Nutrition, the American Journal of Medicine, the Journal of the American Dietetic Association, Scientific American, the American Journal of Cardiology, Obstetrics & Gynecology, Lancet Oncology, Preventive Medicine, and in many other scientific and medical journals. He is the editor-in-chief of The Nutrition Guide for Clinicians and the author of 18 books for lay audiences. In 2015, he was named a fellow of the American College of Cardiology, and he received the American College of Lifestyle Medicine’s Trailblazer Award in 2016. He is an active member of the Medical Society of the District of Columbia, the American Medical Association, and other organizations working to improve health and medical care.