It’s been quiet on this website for a long time while I’ve had my attention on several all-consuming projects. One was the new edition of Vegan for Life. By the time that book was published last May, I was already immersed in an even bigger endeavor which was a 10-year update to The Dietitian’s Guide to Vegetarian Diets, scheduled for publication in October 2021. Co-authored with Dr. Reed Mangels and Dr. Mark Messina, this is a textbook and a comprehensive overview of all aspects of vegan and vegetarian nutrition.


One subject that both books cover is the use of vegan diets for reducing risk for chronic disease, losing weight, or managing heart disease or diabetes. Defining the “best” vegan diet for these purposes isn’t easy. As with just about any topic in nutrition, the research is often conflicting and uncertain.

Among many vegans, there is a prevailing belief that a low-fat, whole foods vegan diet is the standard for healthy eating. Several studies, primarily from the same group of researchers, have associated this diet with weight loss and improvements in blood glucose control and risk factors for heart disease. 1-7 These studies generally use a restrictive version of a vegan diet, eliminating not just animal foods but also encouraging avoidance of nuts, seeds, avocados, and added fats. It’s an effective approach for weight loss for some people, especially in the short term. By emphasizing foods with low energy density, low-fat diets allow consumption of a greater volume of foods sometimes leading to an automatic reduction in calorie intake.8 It’s also possible that dietary monotony through restriction of whole categories of foods (any foods) is associated with lower calorie intake.9

But for a number of reasons, a very low-fat vegan diet may not be the ideal choice for managing chronic disease, reducing risk for heart disease, or even for weight loss.

Low-Fat Vegan Diets Eliminate Heart-Healthy Foods

Although low-fat vegan diets result in reduced blood cholesterol levels and improved insulin sensitivity, this is most likely a result of weight loss, not the absence of fat-rich foods.3 For one thing, the cholesterol-lowering aspects of low-fat vegan plans – higher fiber and low saturated fat content—aren’t unique to these diets. High-fat vegan diets like the Eco-Atkins pattern are also low in saturated fat and rich in fiber and are effective in lowering LDL-cholesterol and improving insulin sensitivity.10 Most high-fat plant foods are rich in unsaturated fats (the exceptions are coconut and palm oils) which lower LDL-cholesterol when they replace saturated fat in the diet. Higher-fat foods like nuts11,12 and perhaps soy foods13,14 have benefits for reducing heart disease risk that appear to go beyond their effects on blood cholesterol levels.  Diets rich in monounsaturated fat may also be beneficial for glucose control in some people with diabetes.15,16 In terms of heart health, there are no benefits to eliminating these foods from your diet.

Low-Fat Diets May Lack the Essential Omega-3 Fatty Acid

You don’t have to pile on fat-rich foods to meet needs for the essential omega-3 fat alpha-linolenic acid (ALA). Just a tablespoon of ground flaxseed, providing about 3 grams of fat, is enough. But this advice needs to be incorporated into any prescription for a low-fat vegan diet and there are instances where it is not. So, this is not really a fault of low-fat patterns, but is more a fault of the advice sometimes given about this eating style.

Low-Fat Vegan Diets Can be Too Low in Protein

In a recent study comparing a low-fat vegan diet with a Mediterranean diet, subjects were more likely to lose weight while eating the vegan diet, but 40% of the weight lost was lean tissue.7 The truth is that it’s hard to lose weight without losing some muscle in the process. And of course, vegan diets can maintain (and build) muscle mass. In this case, though, the vegan diet seemed to be low in protein. Participants consumed a diet that was around 12% protein with an average intake of 1315 calories per day when eating the vegan diet. This works out to 39.5 grams of protein.  Other studies suggest similarly low protein intakes with very low-fat vegan patterns.1,2,6

For the older subjects in the study, this amount of protein is much too low under any circumstances. And it’s also too low for anyone who is experiencing weight loss. Adequate protein consumption along with exercise is important for protecting muscle and bones when calories are restricted.17 All of these considerations are especially important for vegans since those who eat a diet based on whole plant foods probably have higher protein requirements.

Lower protein intake may help explain why, in the vegan vs Mediterranean diet study, the vegan diet was associated with smaller benefits in blood pressure reduction despite greater weight loss. Protein, especially from plants, may be beneficial for lowering blood pressure.18-20 Diets higher in monounsaturated fats – like the ones found in olive oil – are also effective in lowering blood pressure.20,21 A diet that is low in both protein and fat may not be the best choice for treating hypertension, even if it leads to weight loss.

Increasing protein intake on a vegan diet isn’t difficult. It’s a matter of emphasizing legumes over grains, choosing some gently processed foods like tofu, and maybe even more processed foods like veggie meats or protein powders. Yes, a focus on whole plant foods is valuable, but not if it morphs into a fear of all processed foods, including those that might help someone meet protein needs while eating a low-calorie diet.

Low-Fat Diets Are Not Unique for Weight Loss

A meta-analysis of 48 studies found that significant weight loss was achieved with any low-carbohydrate or low-fat diet.22 That is, restrictive diets work no matter what kinds of foods are being restricted. The problem is that many people are less likely to stick with more restrictive versions of diets whether they are low-fat or low-carb.23 Lifelong healthy eating has to involve an eating pattern you enjoy and for many people that’s one that includes higher-fat foods.

Low-Fat Vegan Diets Send a Problematic Message About What It Means to Eat Healthfully as a Vegan

These diets are sometimes touted as a way to lose weight or improve heart health without having to count calories. But, while there are no limits on portion sizes, certain foods are off-limits with this approach.  It’s every bit as restrictive as calorie counting, keto dieting, or any of the many approaches to dieting that are built around stringent food rules. Eating patterns involving elimination of whole categories of foods for weight loss have more in common with fad diet approaches than with a lifestyle approach that focuses on health and enjoyment. For some, it can promote unhealthy perspectives about food. It can also deter people from even considering a vegan diet if they believe that the way to eat healthfully as a vegan is to avoid higher-fat foods. In any case, it’s not an evidence-based principle since there are no foods you have to give up entirely in order to be healthy.

What’s the Best Vegan Diet?

The best vegan diet is one that is rich in fiber, low in saturated fat, provides adequate nutrition, and fits your personal needs, including food preferences, resources, and food availability. Some vegans prefer a low-fat diet and that’s okay. I am not saying that low-fat eating is universally bad. If you ensure adequate intakes of ALA and give extra attention to choosing protein-rich foods, it’s fine to eat a diet that limits higher-fat foods — as long as this is the way you enjoy eating.

But in terms of the way we talk about healthy eating for vegans, there is no reason to believe that a diet that shuns all high-fat plant foods is somehow superior to vegan diets that include nuts, seeds, avocados and vegetables oils. Low-fat diets have no particular benefits for either health or weight loss.


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