For those of you that aren’t familiar with the documentary Forks Over Knives, here’s a brief explanation: the filmmakers discuss the benefit of consuming a plant-based diet (basically a vegetarian-type diet). To their credit, the filmmakers do base what they say on published research. Much of this research was authored by T. Colin Campbell, a former professor at Cornell University. Dr. Campbell conducted his research in China and compared the diets and health statuses among folks living in different provinces. He discovered that those that consumed mainly a plant-based diet instead of a diet full of animal-based proteins (think: meat, poultry, eggs, milk, yogurt, etc.) were healthier, often did not experience the same chronic diseases (like heart disease), and were less likely to be overweight or obese. He eventually summarized these findings in a book called The China Study.
What does this have to do with the documentary Forks Over Knives? Much of what was presented in the documentary is based on the findings discussed in The China Study. The filmmakers actually interviewed Dr. Campbell quite extensively to discuss his research and what it all means.
Is it accurate to say that following a plant-based diet will help someone lose weight, especially given that fruits and vegetables are often full of carbohydrates? And is it possible to consume enough protein when following a plant-based diet?
To say that by simply following a plant-based diet will lead to weight loss is definitely an overstatement. Not everyone will experience weight loss by simply following a plant-based diet. When it comes to weight loss, it really is about the math: calories consumed minus calories burned. If consuming a plant-based diet will lead to fewer calories consumed, it will lead to weight loss. If too many calories are consumed, then they may experience weight gain. This math applies no matter what type of diet a person is following–plant-based, keto, Mediterranean, etc.
I’ll give you an example: I once had a patient that was interested in becoming a vegetarian, not necessarily for weight loss, but because they wanted to improve their overall health. When I saw them for a follow-up visit some weeks later, I asked them how the transition was going and what they had been eating. Here’s what they said: “Oh, it’s been great! For breakfast, I’ll have a large bowl of oatmeal with a glass of orange juice, and then for lunch, I will have a peanut butter and jelly sandwich with a cup of dried fruit on the side, and then dinners are usually a bowl of pasta with a bread roll on the side.”
Ok, so technically, it would be accurate to say that this person was eating a plant-based diet–everything they consumed came from a plant and not an animal. But what I discovered was that this individual actually gained weight since starting their plant-based diet! Again, this was because even though they were consuming plant-based foods, their portions were too big, which led to too many calories consumed. And by adding extra pounds to their frame, they actually were increasing their risk for disease.
Furthermore, while this was technically a vegetarian diet, something critical was missing: the vegetables! Instead of saying this person was following a vegetarian diet, it would be more accurate to say this person was following a “carb-a-tarian” diet!
I want to be clear: carbs alone do not lead to weight gain. Again, it comes down to calories consumed versus calories burned. Plus, not all vegetables are high in carbohydrates.
Commonly consumed vegetables that are higher in carbohydrate:
- potatoes (both regular and sweet)
But, many vegetables are actually quite low in carbohydrate:
- leafy greens like lettuce, kale, and spinach
- bell peppers
- brussels sprouts
At the same time, vegetables contain water and fiber which helps you feel full. Plus they’re low in calories. Because of this, you end up increasing your chances of weight loss.
However, saying that everyone will lose weight following a plant-based diet is an overgeneralization – it depends on what types of foods a person is consuming. Carbs alone will not lead weight gain. But consuming more vegetables for the reasons I just mentioned might help someone lose weight.
What about fruit? Fruit is naturally high in carbohydrate, mostly in the form of natural sugars. Remember, sugar is a type of carb. But whole fruit also is a great source of fiber and water. When we eat dried fruits or drink juice, we lose some of the water or fiber, which can lead to overconsumption. Consuming too much of anything can lead to weight gain.
What I recommend for most people is to consume whole fruit instead of juices, go easy on the dried fruit, and aim to get about 3 servings of total fruit per day. One serving would be like a medium-sized apple or orange, which would be about the size of your fist. When you're shopping for apples, oranges, peaches, or really any round fruit, hold it up with one hand, make a fist with your other hand, and compare them. If the piece of fruit is larger than your fist, it’s more than 1 serving. If it's smaller, it’s less than 1 serving.
If we’re talking about strawberries, for example, 12 large strawberries would count as a serving. Or, ½ cup of dried fruit like dried apricots would count as 1 serving.
And, finally, what about protein? We’re learning that those that follow a mostly plant-based diet get plenty of protein each day. They also tend to get the kinds of protein that help build muscle. One of the biggest myths in the fitness industry is that animal proteins are necessary for muscle growth. What many don’t realize is that plant-based proteins often contain the same amino acids (amino acids are really most important when it comes to muscle growth) as animal-based proteins.
The bottom line is this: carbs alone don’t lead to weight gain. Following a plant-based diet will not necessarily lead to weight loss. This is really based on the quality of their diet and the total calories they consume. And those that follow a vegetarian diet will still get enough and the right types of proteins to grow muscle.