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How to Gain Weight on Diet Soda

Erythritol, the too-good-to-be-true nontoxic, low-calorie, tooth friendly sweetener that I profiled in my last blog post “Is There a Safe, Low-Calorie Sweetener?” may even act as an antioxidant. So what’s the catch?

Well, there are three ways that all low-caloric sweeteners could theoretically be harmful independent of their specific chemistry. As I report in my 2-min. video How Diet Soda Could Make Us Gain Weight, several large studies have found an association between artificial sweetener use and weight gain, meaning the people that drank the most diet soda, for example, gained the most weight. The most common explanation for this counterintuitive finding is what’s called reverse causation. People aren’t fat because they drink diet soda; they drink diet soda because they’re fat!

But there are at least three less benign alternative explanations. The first is called “overcompensation for expected caloric reduction.” If you covertly switch someone’s soda for diet soda without him or her knowing it, his or her caloric intake drops. Obviously, right? They’re not drinking all that sugar anymore. But what if you tell them what you did? People who knowingly are consuming artificial sweeteners may actually end up eating more calories. Why? Because they’re like hey, I’m drinking diet soda, so I can have two pieces of cake.

One of the studies I profile involved giving people an artificially sweetened cereal for breakfast, but only half were told. When it came to lunchtime, the group that knew they had eaten an artificially sweetened cereal ate significantly more than those that didn’t know any different. Basically, it’s the diet-soda-with-a-fast-food-meal syndrome. One may only lose weight on diet soda if you don’t realize it’s calorie-free.

The second reason even the most harmless noncaloric sweetener could still be harmful if we’re not careful has to do with how our brain is wired. Watch my 2-min. video Neurobiology of Artificial Sweeteners to learn how the disconnect between sweetness sensations coming from our tongue and the lack of a caloric feedback loop in the gut may result in overeating.

Finally, all sweeteners–natural and artificial, caloric and non-caloric—help maintain cravings for intensely sweet foods. As I explain in my 2-min. video Unsweetening the Diet, if you go on a low salt diet, for the first few weeks everything tastes like cardboard until your taste buds have a chance to adapt to the new norm. After that, natural low sodium foods taste perfectly fine and adding table salt tastes gross because it’s way too salty. Same thing with the sweeteners.

At home maybe you use a harmless sweetener like erythritol—that’s great, but then what if you go on vacation and forget it at home? You still take your preference for severely sweet food with you and that may end up translating into the increased consumption of less than healthy foods.

So those are the caveats for even nontoxic sweeteners. They are only safe if you don’t use them as an excuse to eat more junk food.

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

13 responses to “How to Gain Weight on Diet Soda

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  1. I bought erythritol and saw that it came from corn, but did not say organic or non GMO. Is there an organic variety of this?

    1. The erythritol sold by NOW Foods, which I buy, claims to be non-GMO, but doesn’t claim to be organic.

      Most of the production expense arises from fermenting the yeast Moniliella tomentosa var. pollinis on corn glucose and refining and crystalizing the erythritol from the fermentation vat. The cost advantage from using glucose from common GMO #2 feed corn rather than sweet corn varieties (none of which to date are GMO) is probably negligible. Corn syrup solids are cheap (< $1/lb), even when made from sweet corn that doesn't make it to the produce or frozen aisle.

      I personally wouldn't mind GMO erythritol, but this isn't the forum for that discussion.

      1. I would avoid unless it can be verified to be Non-GMO, such as the Non-GMO Project. Why not write NOW foods and ask if it is verified to be Non-GMO (Project). Lots of companies that are non-GMO are signing up.

  2. One of my biggest resentments is that I was never protected by the medical profession as a child.

    My personal estimate is that most overweight people are carrying a large trauma load and use food to moderate the pain. I do.

    It behooves us all to be careful about labels that are really propaganda.

    Very best regards,


    1. I had the opposite happen to me. As a child I was very underweight. I could finish my meal and finish everyone else’s and not gain an ounce…until I left for college. Then, everything changed. And for the first time in my life, I had a weight problem having gained 20 pounds first semester.

      It was a combination of my growth cycle stopping, and being free from am overbearing mother so as to eating anything I wanted. Eating the wrong foods quickly added weight to my then, 5’9″, 118 pound frame.

      Now, with a constant weight problem and my constantly trying to weigh less while at the same time get the nutrition I need to counter osteoporosis in my bones, I find myself confused at best and trying to figure out how to jump start my weight loss again. But most doctors don’t know nutrition and are pill pushers, and most big labels are not truthful. One needs to understand the barely visible fine print. And, remember, it’s what is not said, can be most important!

      1. Beccadoggie10, the best way to regain proper health is to give your body what it needs and craves… Fruits and Vegetables and nuts and seeds and beans!!! It can be hard giving up the foods that we know and think we love, I am personally well aware of this myself, but know that you always have support here and science to back that support up!!!!

  3. Remember, sweetners are not just to sweeten. They are also to balance against tart, bitter, sour, and salty flavors. It’s only when they are dominant (either alone or in greater quantity) that they promote a sweetness preference. Nothing wrong with adding a little erythritol to hibiscus tea for example. hibiscus is tart. The z-sweet will just reduce the tartness of the tea, not make it sweet unless you overdo it.

    1. How is that physiologically possible since insulin isn’t released until glucose levels are elevated in the circulatory system? Have some studies been conducted to indicate that this does happen? thanks

  4. I am a dedicated follower of Dr. Greger who I have discovered lately.
    I had cervical cancer 13 years ago which I have survived so far and am currently in a pre cancerous state with high TKTL1 and APO 10 levels.
    I am 167 cm tall and lost a lot of weight due to a stressful life during years. My weight is 44 kg, 2 years ago I had 60 kg.
    I really want and need to gain weight but do not see how I can hit this aim with only plant based nutrition. Hopefully I am wrong and I would be pleased to get some supportive comment.

  5. I love erythritol, especially given its antioxidant chemical structure, BUT I just saw this Cornell paper suggesting it may play a key role in the formation of belly fat!!!

    Please have someone burst into Dr. Greger’s office immediately and ask him to issue a judgment on this!!! My future six-pack may be in peril! I’m sure Dr. Greger will understand the crucial nature of this urgent request. LOL, but this is serious for those of us working out! Thanks!

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