There’s a host of benefits of going vegan, from lowering your risk of certain diseases to helping to save the planet. There’s also a growing body of evidence of the power of a plant-based diet in promoting weight loss, and now we’re intrigued to see one more study join the mix. Published in the peer-reviewed journal Nature Medicine, the study “Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake” took a look at the difference between a plant-based, low-fat diet and an animal-based, low-carb diet, to see how each impacted weight loss.
New Study Compares Plant-Based Diets with Keto Diets
Conducted by researchers at the National Institute of Diabetes and Digestive and Kidney Diseases, the study tracked 20 adults without diabetes for four continuous weeks in the NIH Clinical Center’s Metabolic Clinical Research Unit, providing them with three meals daily and snacks and allowing the 11 men and nine women to eat as much as they wanted. They all received the plant-based, low-fat diet or animal-based, low-carb diet for two weeks, directly followed by the alternate diet for two weeks.
“High-fat foods have been thought to result in excess calorie intake because they have many calories per bite. Alternatively, high-carb foods can cause large swings in blood glucose and insulin that may increase hunger and lead to overeating,” said NIDDK Senior Investigator Kevin Hall, Ph.D., the study’s lead author in the NIH press release. “Our study was designed to determine whether high-carb or high-fat diets result in greater calorie intake.” Scientists then compared the results of these diets on calorie intake, hormone levels, weight, and other factors.
Low-Fat Plant-Based Diet Leads to Less Calories Consumed
Interestingly, researchers discovered that those on the low-fat diet consumed 550 to 700 fewer calories per day than when they ate the low-carb diet. Even though they were eating substantially fewer calories on the plant-based, low-fat diet, “study participants reported no differences in hunger, enjoyment of meals, or fullness between the two diets. Additionally, participants lost weight while on both of these dietary patterns, but only the plant-based, low-fat diet “led to a significant loss of body fat.” Future research would need to be conducted to see how these results stacked up over a longer period of time.
Ashley Shaw, Registered Dietician for Preg Appetit!, who wasn’t associated with the research, broke down these exciting findings for us, further, saying “currently, animal-based, high-fat diets are very popular for weight loss (i.e., keto, paleo) so this is positive news for those that are vegan/vegetarian, or just want a more plant-based lifestyle and also want to lose weight.” She did note, however, that while the plant-based diet led to greater body fat loss when compared to the animal-based diet, that those on the plant-based diet had less stable blood sugar.
The study found there were several other benefits to eating plant-based, beyond weight loss. “Those consuming the plant-based diet could consume bigger portions because the foods are lower in calories per gram of food compared to the animal-based foods,” said Shaw, also noting that the plant-based diet contained much more fiber, which helps keep your appetite at bay. “This means that while those on this diet could eat more due to it being lower in calories, they were actually more likely to eat smaller portions,” she added. Eating a fiber-rich diet from fruits, veggies, grains, and beans, is also linked to a variety of positive health outcomes, including reduced risk of cardiovascular disease and cancer. (For more on fiber and its health benefits, check out this article.)
A Whole-Foods, Plant-Based is Also Linked to Weight Loss
Beyond the latest study, there are many reasons experts believe going vegan can help promote weight loss. “A vegan diet is rich in heart-healthy fats and fiber, which together can be extremely beneficial for weight loss. Polyunsaturated fats actually help the body to metabolize fat for energy, whereas fiber makes you feel fuller faster and stay satisfied longer after a meal. That means smaller portions go a long way, and fewer calories are consumed,” said Shaw, further commenting that everyone is different, and for some, a higher fat diet is better for weight loss while others may need a higher carbohydrate or higher protein diet.
“What I like about this study is that it gives vegans/vegetarians an option since most plant-based food is higher in carbohydrates. This proves that keto is not the only option for weight loss, and may not even be that good of an option for those who consume animal-based foods,” Shaw continued. One important caveat, this study was designed in a tightly controlled laboratory setting: “A main factor of this study was that the foods consumed (whether plant- or animal-based) were minimally processed, something that is not as easy to achieve outside of a controlled environment,” she said, highlighting — on the plus side — that many who adhere to plant-based diets are more likely to eat foods that are minimally processed and more wholesome overall than those eating a standard American diet.
As Michele Sidorenkov, RDN cautions, there are certainly some high-carb, vegan diets that are unhealthy and can lead to weight gain. “I have heard of the term ‘junk food vegan,’ which is someone who consumes a lot of processed, packaged vegan foods, like cookies and frozen snacks,” she said. “While a junk food vegan could fit into the category of eating high-carb vegan meals, they will not get the same weight loss or satiety as described in the research study…There are many ways someone could eat a high carbohydrate vegan diet, and they don’t all result in weight loss.”
Despite the potential for unhealthy adaptation of a plant-based regime, as with any diet, Sidorenkov gives eating vegan the green light when it comes to slimming down. “Personally, I do feel like a vegan diet could be beneficial for someone who is trying to lose weight if the diet is sustainable, the person is feeling satisfied and not deprived, and they are including the proper amounts of plant-based proteins, carbohydrates, and healthy fats into every meal,” she explained.
Sample Meal Plan for a Low-Fat Plant-Based Diet
For an example of what a nutritious day of plant-based eating could look like that follow a plant-based, low-fat diet, Shaw recommends the following:
Breakfast: Tropical smoothie with frozen mango and pineapple chunks, banana, baby spinach, hemp hearts, and nut milk of choice. (We love this refreshing mango and banana smoothie recipe.)
Lunch: Sprouted multigrain bread with nut butter and strawberry slices sprinkled with chia seeds
Dinner: Homemade burrito bowl with black beans and brown rice with Tex-Mex spices over a bed of lettuce topped with avocado, tomato, onion, jalapeño, and salsa.
Snacks: Peanut butter or almond butter with apple slices; hummus with carrot and celery sticks; guacamole and bell pepper strips.
On that note, we’ve got a mango smoothie to prep for tomorrow morning. How delicious does this meal plan sound?