Can you lose weight on a plant-based diet? How?

It’s a common question, can you lose weight on a plant-based diet? While nutrition science supports numerous health benefits of replacing animal foods with fiber-rich plant foods, such as lowering all-cause and cancer-specific mortality, reduced blood pressure, reduced risk of type 2 diabetes and cardiovascular disease, the effect of a plant-based diet for weight loss is not as clear. 

Weight loss studies are complex with a variety of factors, such as the amount of calorie restriction, as well as the type of dietary pattern (i.e., low fat, low carbohydrate, vegetarian, etc.), and therefore it’s challenging to assess the effects of a specific diet from behavioral changes, such as tracking calories, monitoring portions, timing of meals, etc. In addition, evaluating the effectiveness of a plant-based diet for weight loss poses its own challenges as there are several types of plant-based dietary approaches. 

Understanding plant-based diets for weight loss

Not all plant-based diets are the same – there are numerous types of eating patterns that fall under the plant-based diet umbrella. A vegan diet eliminates all animal products (meat, poultry, seafood, dairy, eggs and honey) and strictly consists of plant foods, whereas a lacto-ovo vegetarian diet includes dairy products (milk, cheese and yogurt) and eggs and a pescatarian diet includes seafood (fish and shellfish), but neither include red meat, pork or poultry. 

There is promising data from one of the first meta-analyses to focus on vegetarian diets and weight loss by Huang and colleagues in the Journal of General Internal Medicine. The results revealed that a vegetarian diet might accomplish modest weight loss in persons who are overweight or obese. The data evaluated weight loss outcomes in 12 randomized control trials with 1,151 participants: eight studies with vegan diets, four studies with lacto-ovo diets compared to non-vegetarian diets. The downside is that the evidence base was small with only 12 short-term studies, which ranged from 8 weeks to 2 years. The research revealed that participants on a vegetarian-type diet lost 4.4 lbs more weight than those on a non-vegetarian diet. Whether or not participants kept the weight off long-term is not known as most of the studies did not last longer than 6 months. 

Plant-based diets vs. other weight loss approaches

Weight loss diets come in many varieties from the popular low-carbohydrate and low-fat approaches to plant-based diets to omnivores. Research shows that low-carbohydrate and low-fat diets are associated with more weight loss than no intervention over a one year period. What about plant-based diets for weight loss? In a study, which specifically looked at five plant-based diets on weight loss, including vegan, vegetarian, pescatarian, semi-vegetarian and omnivorous, which took place over 6 months and was completed by fifty overweight participants who were randomized among the diets, the vegan diet showed the greatest amount of weight loss with -7.5% body weight versus the other diets, which were a little over 3% weight loss.  The researchers found that the vegan dieters ate less total fat, as well as saturated fat, than those on the other diets. Since fat is the most calorically dense nutrient, the vegan diet contained less calories than the other diets.  

The macronutrient composition of the plant-based diet for weight loss can play a role in its success. In a small study, which consisted of twenty women with a mean BMI of 31 participated in a 6 week “healthy plant-based diet” intervention in which they ate whole grains, fruits, vegetables, nuts, seeds and hydrated with water, weight loss was assessed. The participants were not limited to a specific calorie level and were encouraged to eat fiber-rich foods to increase feelings of fullness. Fiber is only found in plant foods and plays a key role in weight loss as it stabilizes blood sugar and helps fend off insulin resistance, which can decrease cravings for refined carbohydrates.  

The first three weeks was a ‘reset phase’, which eliminated all refined sugar, heavily processed foods, artificial sweeteners, alcohol, meat, fish, dairy and oil for the participants’ diets. The study protocol offered nutrition education, group support opportunities, a closed Facebook group, recipes and shopping lists. After 6 weeks, 17 of the 20 participants completed the study and those following the healthy plant based diet lost 9.6 lbs (4.4 kg) and reduced their BMI from 31 to 29 – plus as a result of following this plant-based diet, they increased their fiber intake, reduced saturated fat and cholesterol intakes. 

There are some challenges of following a plant-based diet for weight loss as finding the right balance of macronutrients can be difficult. It can take more creativity to get enough protein in the diet. Plant proteins include beans, lentils, quinoa, amaranth, as well as tofu, tempeh, seitan, nutritional yeast, nuts, nut butters and seeds. Many plant diets contain more carbohydrates than necessary, which may prohibit weight loss. By eliminating refined carbohydrates (i.e., cookies, cake, candy and soft drinks) and focusing on complex, high fiber carbohydrates weight loss can happen more easily on a plant-based diet.

How to lose weight on a plant-based diet

However, how to lose weight on a plant-based diet is no different than other weight loss approaches – it’s about creating a calorie deficit. Studies revealed that it’s not only eating plant-based that helped with weight loss, but restricting calories was beneficial, too. Study participants who followed a vegetarian diet intervention with a calorie restriction achieved more weight loss (-4.4 lbs vs. -3.5 lbs) than those who didn't restrict calories. The authors concluded that “regardless of the diet that patients consume, reduced calorie intake remains the bedrock of behavioral weight loss interventions.”

Weight loss aside, not all plant-based diets translate to healthful outcomes and the quality of calories count in the overall health equation. A plant-based eating pattern of whole vegetables, fruits, whole grains, nuts, seeds, legumes, olive oil, as well as coffee, tea, herbs and spices is lower in calories, higher in fiber and beneficial unsaturated fats, antioxidants, vitamins and minerals, which can help reduce risk for chronic diseases. On the other hand, a less healthful plant-based eating pattern of juices, sweetened beverages, refined grains, fried foods and sweets is high in calories, saturated fat, added sugar, and sodium, which may increase risk for chronic diseases, such as heart disease, type 2 diabetes, certain cancers and obesity. 

Regardless of the type of plant-based diet, the basic tenets of balance, portion control and mindful eating for weight loss still apply. Balance your meals and snacks with fewer processed plant-based products and incorporate more whole fruits and vegetables. Keep it mind, it helps to portion control starchy vegetables, such as pea, potatoes and corn, as well as grains like pasta, rice, quinoa and couscous for weight loss. Practice mindful eating by slowing down, chewing your food well and taking at least 20 minutes for a meal to allow your brain enough time to register feelings of fullness without overeating.  

Meal planning and prepping on a plant-based diet for weight loss is ideal for successful outcomes. Gather weekly plant-based recipes that you want to try and/or keep a dry erase board and jot down your meal plan for the week. Running out of ideas of what to make for dinners? Set theme nights, such as ‘Taco Tuesdays’ or ‘Grill Out Wednesdays’ or ‘Pizza Fridays’.  You’ll be more apt to stick with your meal planning and prep if you have an agenda. 

Keep meal prep simple with pre-cut vegetables and fruits, steamer bag vegetable blends and frozen fruits and vegetables. Don’t be afraid to get frozen produce as it’s flash frozen at the highest point of nutritional value – as soon as it’s harvested, making it a super nourishing and convenient option. 

Remember, protein is essential on a plant-based diet for weight loss. Contrary to popular belief, just because you don’t eat meat, doesn’t mean you are not getting adequate protein. There are numerous plant-based proteins to get creative with for meals and snacks. 

There are a variety of ways to boost protein intake on a plant-based diet.  You can add tofu, edamame, tempeh, soymilk and beans and lentils to meals and snacks. Try complete protein grains, such as quinoa, sorghum, buckwheat and millet with your favorite vegetable medley.  Add plant protein powder to a fruit and vegetable smoothie. Grab a handful of nuts as a snack or spread nut butter on to a piece of whole grain toast or apple slices.  

The bottom line

A plant-based diet for weight loss relies on the interplay of how much you eat throughout the day and choosing nutrient-dense plant foods, which are jam-packed with fiber to help fill you up faster and longer, stabilize blood sugar and insulin levels to fend off sugar cravings, and to keep your gut microbiome balanced to help keep your metabolism humming along efficiently.  Keep in mind, a plant-based diet for weight loss is not a quick fix and only works if the diet is sustainable and can be adhered to over the  long-term.   

Delicious meal ideas for plant-based weight loss

Tofu grain bowls

• Dice extra-firm tofu, marinade and bake it to toss into a bowl with your favorite whole grains and dressing.

Grilled tempeh and vegetables

• Slice tempeh, toss it in a sesame soy marinade and grill it with vegetables. Serve over brown rice.

Beany baked potatoes 

• Toss chickpeas or black beans into a salad or slaw and spoon onto a plain baked potato. 

Mediterranean chopped salad

• Chop leafy greens, tomatoes, cucumbers, red pepper and kalamata olives and toss in walnuts, pecans or almonds and drizzle with a balsamic vinaigrette.

Chia pudding cups

• Make a batch of chia pudding with your favorite dairy or plant milk and top with cinnamon and berries for tasty breakfasts during the week. 

Seitan stir fry

• Stir-fry seitan in a wok with a vegetable medley and serve over brown rice or noodles. 

Nut butter and berry toast

• Spread nut butter on a slice of whole grain toast and top with your favorite berries. 

What you should know before going plant-based

For help achieving realistic weight loss goals with an individualized eating plan, consider working with our weight loss expert team of doctors and registered dietitians at Form Health. They can help you understand what plant-based diet is right for you, how to meal plan using a variety of plant foods, and establish a plant-based approach that can offer long-term weight loss success. To find out if you are eligible for the Form Health medical weight loss program, take our quiz today!