I've heard many places (just google the title of this question) that a vegan diet causes weight loss, usually in the context of trying to lose weight.

Does a healthy vegan diet actually cause weight loss? i.e. getting all the nutrients I need, getting protein, etc.

Note: I'm talking about switching to a standard vegan diet, and assuming a vegan diet is the only change made. (i.e. replacing all non-vegan foods with vegan alternatives)

I'd prefer answers to exclude any data from people attempting to lose weight, i.e. I'm asking about eating vegan, not eating healthier. (even though there is some overlap)

  • Not if you are actually trying to. Vegan diet contains all the necessary carbs and proteins. So if you eat just right there would be no weight loss. – Dipen Shah Jan 31 '17 at 19:15
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    I'm dubious as to whether this is a workable on-topic question for the site, as there are going to be many different and very subjective answers (and a lot of garbage.) That doesn't mean it was wrong to ask it, though - we're here to find out what works and what doesn't, after all! – Pekka 웃 Jan 31 '17 at 19:19
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    @Pekka웃 yeah, I figured as much. – Riker Jan 31 '17 at 19:20
  • So the context of your question excludes any cases of "lost weight going vegan/vegetarian because of, at the same time, changing to a healthier diet, or to more home cooked food, or cooking so much it became exercise?" – rackandboneman Mar 13 '17 at 9:09
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    I think this question is fine, as long as you take the "scientific-studies" tag seriously. I.e., not everyone can just add a subjective opinion, an answer should either provide studies or be downvoted. (I fear my own one is not great either, but I wanted to refute the other one, and at this I think I succeeded pretty well) – Nobody Apr 1 '17 at 10:06
up vote 12 down vote accepted

With a vegan diet you're not sure to lose weight but you're very likely to. According to a research paper, based on about 65 thousands of people, vegans were showing lower BMI than vegetarians and omnivorous (this means they were thinner).

Also in several other clinical trials (Barnard 2009; Jenkins 2009; Barnard 2005; Barnard 2006; Ornish 1998) the adoption of a vegan diet caused patients' weight loss.

graph

UPDATE:

I recently found a meta-analysis of RCTs on vegetarian diets and weight loss. The conclusions seem to be clear:

Twelve randomized controlled trials were included, involving a total of 1151 subjects who received the intervention over a median duration of 18 weeks. [...]

Overall, individuals assigned to the vegetarian diet groups lost significantly more weight than those assigned to the non-vegetarian diet groups. [...]

Vegetarian diets appeared to have significant benefits on weight reduction compared to non-vegetarian diets. Further long-term trials are needed to investigate the effects of vegetarian diets on body weight control.

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    Two big problems: 1) is causation established or correlation? 2) BMI is not a good measure for fat or fitness outside of children and the very heavy. For typical adults muscle mass is too huge a factor to discount. – djechlin Feb 1 '17 at 0:54
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    For the average person BMI is decent metric - which is why it's still used in many studies (though not used for athletes and bodybuilders, for example). An ideal BMI is between 18.5 to 24.9. The graph's scale is chopped which makes the BMI of 20 look really low, but it's normal. – Joe Feb 1 '17 at 1:07
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    @djechlin check the clinical trials. – Attilio Feb 22 '17 at 16:08
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    AFAICT the jama study is only measuring cholestrol. I'm not sure how to interpret "The study food was provided at 60% of calorie requirements." which would definitely induce weight loss if that's all they ate. – djechlin Feb 22 '17 at 20:51
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    @djechlin, actually, this is exactly what BMI was designed for and should be used for: population studies. When applied to an individual, BMI is a poor proxy for body-fat percentage, but when applied to a population, all those individual variations average out. – Mark Mar 24 '17 at 1:51

The Standard American Diet now comes in vegan.

More on that below.

In my anecdotal experience, losing weight simply by going vegan is less likely than one might think and indulges in magical thinking. I am skeptical of studies I have seen so far, in the sense that they have not passed sanity checks regarding correlation v. causation, long-term impact and relying on proper measures, i.e. body fat percent over BMI. Therefore I would take this anecdote as pretty serious evidence (but weigh it against data-driven studies of course).

The trend of losing weight from going vegan seems to match that of any other diet. (here is a graph comparing three diets; IIRC I have seen bigger studies showing the same curves). Enthusiasm in a lifestyle change in itself seems to pay off. Beyond that, it is rubbish to claim a vegan diet by itself is healthier.

A modern vegan diet may include:

  • Soda
  • Bagels
  • Vegan cream cheese, that is a block of soy oil
  • Vegan cookies, cakes, ice creams, etc. that replace dairy with hydrogenated oils
  • Granola bars galore
  • Coconut milk for anything that needs saturated fat added to it
  • Oreos
  • Breads, crackers, chips

And may promote bad habits such as:

  • getting lazier and lazier with real foods and replacing it with processed foods
  • Seamless and Grubhub
  • replacing the usual processed yogurts and cream cheeses with the ultra processed vegan versions, which double down on sugar or hydrogenated fat as necessary
  • the same old susceptibility to food fads that add empty calories, like protein shakes and switching to diet sodas
  • depending on the person, occasionally "cheating" with non-vegan foods, which will certainly never be on a food that is good for you
  • ability to eat at 10 pm or 2 am just the same

Nutrition is a very difficult science in which data does not give final proof.

There is a very good chance I wrote up what your vegan diet may actually look like. You will not lose weight on that. If the study says you will, it was sampling people with access to different foods as you, coming from different cultures, with different health needs.

Studies may tease out an irreducible advantage to being vegan but please take nothing for granted. If you are interested in the art of eating real, whole foods and pursue that best as a vegan, please do so! But do not rely simply on being vegan for your health.

How to lose weight according to Michael Pollan: Eat food, mostly plants, not too much.

As a vegan you have the "mostly plants" down and I might venture it is the least important of the three. You want to be off processed foods to a high extent, and you want to not be eating too much. If veganism brings you closer to those goals then it will probably good for you. If not, the your waistline may not change much.

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    "Honestly, probably not." I think that should be "Often, but not necessarily." Or something along those lines. Most people transitioning to a vegan diet do lose weight (as demonstrated by several studies, some quoted in @Attilio's answer), and end up having a healthier BMI than omnivores, on average. Great answer, otherwise :) – Joe Feb 1 '17 at 0:58
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    @JoeRocc brushed this up a bit. – djechlin Feb 1 '17 at 1:17
  • "hard science" has a specific meaning that I don't think you're intending here. You might consider a different phrasing such as "Nutrition science is difficult" – nloewen Mar 6 '17 at 14:32
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    "getting lazier and lazier with real foods and replacing it with processed foods" - yes, but once you set up the instinct to actually examine what you are buying/eating - which is always the case with vegetarian/vegan people - it is not THAT likely unless done with intent or abandon :) – rackandboneman Mar 13 '17 at 9:12
  • @rackandboneman I assure you not all vegetarians mind what their are eating beyond not coming from animals – ecc Mar 13 '17 at 15:57

Not automatically, no. With any dietary change there will be healthy and not so healthy ways to do it. To become vegan and maintain or lose weight rather than gaining it you have to be careful of adding extra calories.

Some things I've read have suggested that it is often the case that vegan meals have a lot of the "tasty" non-vegan things like cheese and dairy taken out of them, and the easiest way to make them more tasty is to add lots of oil and other fats.

If you switch to a vegan diet whilst trying to lose weight, then it may be helpful but that's likely because in order to be vegan you have to take more care over what you are cooking. If you took more care over your existing diet (be it vegetarian or not) then you could lose weight that way too.

The long and short of it is: No, a vegan diet is not a "magic bullet" to losing weight, if that's what you're asking.

  • Do you have a source to back this up? – Riker Dec 13 '17 at 2:35

It's depends on if you make other healthy lifestyle choices. Studies just comparing BMI and diet may be affected by confounders: Vegans are often choose to their lifestyle due to concerns about health and the environment.

There is no universal vegan diet, there are a lot of personal choices involved and any study may not be representative of your actual diet. The results of the studies (even if they showed Vegans have lower BMI) may be unreliable. For instance, if:

  • They're more likely to eat modest portion sizes, exercise, or cycle to the office.
  • They're less likely to eat fast food regularly or drive short distances.

That doesn't intrinsically make it a healthy lifestyle choice for individuals in of itself. You won't magically shed weight as soon as you go Vegan if you're overweight. You won't necessarily be at risk of weight loss or anoxeria either. It depends a lot on what you did and ate before and whether you make other healthy choices in your life.

So yes, Veganism is potentially a healthy diet and weight loss is possible but it will still take effort to break bad habits. It will be a lot harder to get Vegan-friendly McDonalds at 3AM after a few too many drinks but it is still possible to eat junk food and not exercise very often. It’s still your responsibility to make healthy choices.

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    This question is tagged "scientific studies". You make several claims which depend on data (as compared to basic logical thinking which doesn't need citations). Please add a scientific study for each one. – Nobody Apr 1 '17 at 10:08
  • Sorry, I was unaware that this tag had that requirement. This is really a critique of the answers which based claims on findings such as the Oxford study (Davey et al., 2003). It more about the implications of population studies for an individual. I've reworded for a logical (statistical) argument. Health and environmental reasons for Vegan/Vegetarianism have been discussed at length on this site. – Tom Kelly Apr 1 '17 at 10:19
  • Yeah, I supposed it's similar to mine, both mostly just critique the currently accepted answer, but don't answer the question as asked. – Nobody Apr 1 '17 at 10:24
  • Well the question does ask about causation. A population study won't establish that as it's simply too complicated to account for all of these variables. The only way would be to lock people into room and make them switch to vegan while consuming exactly the same number of calories as before. That's unlikely to work and highly unethical. No feasible study can address this. Although I suspect the OP didn't want to discuss study design anyway as the tag is a retcon. – Tom Kelly Apr 1 '17 at 10:31
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    Basically, you're going to have to be a statistical ninja to provide any definitive link between Veganism and weight loss. What's the point? We should be encouraging these other healthy lifestyle choices anyway. – Tom Kelly Apr 2 '17 at 1:42

Google your TDEE:
if you eat over that number you will gain
if you eat under that number you will lose

It doesn't matter if you eat vegan or not vegan; weight loss/gain/maintaining comes down to calories.

I have been losing on a high carb plant based diet. (Yes, I am vegan.)

It depends on what you eat. Fruit and vegetables will have less calories and more nutrients. Flax and chia seeds are good to incorporate. I limit high fat seeds and nuts as they are limited in a high carb diet, but I do eat them occasionally as they do have benefits too. Processed foods can cause weight gain as they are usually high in fat, salt, and/or sugar. There are some tasty vegan/vegetarian products, but a wholefoods diet is best.

If you're interested, Dr McDougall and Mary McDougall have several books on this. Chef AJ and High Carb Hannah have recipes and books of their own.

Vegan food is incredibly more caloric dense and nutrient rich than meats. That's why high protein diets are used to lose weight, low carb diets were born because of this, meat has few calories and fills you up.

The Effects of Increased Protein Intake on Fullness: A Meta-Analysis and Its Limitations

It is easier to gain weight with a whole food vegan diet because you are restricting yourself to eating high caloric and nutrient rich foods instead of wasting stomach space with useless meat.

  • Meat(muscle) has generally around 250-270 kilocalories per 100 grams
  • Liver has around 165 kilocalories or less per 100 grams
  • Eggs have 155 kilocalories per 100 grams, most of which is pure fat.
  • Grains have generally around 330-375 kilocalories per 100 grams
  • Beans(dry weight) have generally 330-480 kilocalories per 100 grams
  • Nuts have generally 560-680 kilocalories per 100 grams
  • Oils have generally 800-950 kilocaries per 100 grams

Source: Nutritional value of foods written on packages

The only caloric rich tissue present in animals is fat, but nobody eats pure lard in their diet in the modern day.

Those are the most consumed foods in the entire history of humanity, just look up the mediterranean diet, literally based on olive oil, grains and legumes... or any asian diet.

For example my first two meals for today were : 204 grams of muesli (990 kcals) + 250 grams(98 kcals), then just a few minutes ago 150 grams of pasta, by dry weight (534 kcals) + 100 grams of bread (280 kcals).

In only 2 meals I consumed 1930 kcals, not even counting the sauce from the cooked pasta, which is a lot because just a spoon of olive oil sits at around 124 kcals. Every time you eat meat you are consuming less calories than you could if you simply ate some vegan food instead.

But what about veggies? well, the most consumed foods in the world are grains not veggies for a reason.

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    Can you provide sources for this info? This question is tagged scientific-studies, so it's necessary to source your information reliably. Personal anecdotes are not really scientific nor from studies. – Riker Nov 24 at 1:03
  • Please take your conversation to chat, folks :) – Erica Nov 26 at 14:29
  • Comments are not for extended discussion; this conversation has been moved to chat. – Erica Nov 26 at 14:29
  • @Erica okay, I'll stop here, but the math still doesn't add up :) – henning Nov 26 at 14:29

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