RCT Says Vinegar Works for Weight Loss. Is It Credible?

RCT Says Vinegar Works for Weight Loss. Is It Credible?

It sounds pretty good. A new study popped up last week in the Journal of Functional Foods. It’s a randomized, controlled trial (RCT) of apple cider vinegar added to a reduced calorie diet for weight loss. Solaleh Khezri and colleagues found that people lost a bit more weight if they consumed a tablespoon of vinegar on their salad at lunch and dinner, compared to the control group who didn’t.

So what are we supposed to think?

A Small, Well-Controlled Study

This is a small, but reasonably well-controlled study. The protocol randomly assigned people to two different groups that each followed the same diet – one that reduced their daily calories by 250 from what would it would take to maintain a constant weight. But one group put a tablespoon of apple cider vinegar on their salad at lunch and dinner.

The study ran for 12 weeks.

A Small, Short-Term Benefit

At the end of 12 weeks, the control group lost an average of five pounds, 2.8% of their initial weight. The vinegar group lost 8.8 pounds, 4.8% of their starting weight. That’s a modest benefit, but the authors found that it was statistically significant (p=0.01). We would call that a pretty small benefit for what might be a small risk. The biggest risk could be that a person would get sick of eating that much vinegar on a salad twice a day, every day.

But on the other hand, the authors included absolutely no information on adverse effects in their paper. And even if they did, a sample size of 39 is totally inadequate for documenting safety.

How does it work?

Another reason to think twice about this is the likely mechanism of action. A 2014 study in the International Journal of Obesity explored how vinegar might work. Julia Darzi and colleagues concluded that consuming vinegar does indeed suppress a person’s appetite. It wasn’t the taste or smell. It was a physiologic effect of the vinegar. After consuming it, people felt mildly nauseated. They concluded that this use for vinegar “does not seem appropriate.”

We agree with Darzi et al. Nausea is a poor tool for losing weight. And most likely, it’s not a long-term solution that anyone can tolerate.

Click here for the Khezri study and here for the Darzi study.

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February 19, 2018

9 Responses to “RCT Says Vinegar Works for Weight Loss. Is It Credible?”

February 19, 2018 at 7:33 am, Al Lewis said:

I’d say a good rule of thumb is that any study showing weight loss or any other health benefit by consuming a daily tablespoon of any household staple, is wrong,
February 19, 2018 at 8:42 am, John DiTraglia said:

A tablespoon on my salad doesn’t sound so bad. Italian dressing with olive oil. The Mediterranean diet.
- February 19, 2018 at 11:51 am, Ted said:
  
  My initial reaction was similar, John. But then I thought about a whole tablespoon of vinegar twice a day every day. I could see it getting old fast. Very different from having a little bit whenever I want.
February 19, 2018 at 9:20 am, Angie Golden said:

Interesting. I have had three patients in the last couple weeks ask about taking apple cider vinegar twice day to supplement their eating plans. Thanks for the information.
February 19, 2018 at 12:04 pm, Frances Kuffel said:

Dear Ted:

I do social media for both Pam Peeke and Amy Myrdal Miller and I use your posts frequently. I have a question about this post and two comments.

The first is, who or what does “RTC” stand for?

An improvement of 2.8 – 4.8% is not really modest: it’s a few decimal points away from doubling weight loss.

My second comment is the apple cider trick has been going on for YEARS, featured in women’s magazines and the numerous obesity alerts I read every day. I’ve doubted its efficacy so it’s good to see some actual data on the practice.

If you could identify RTC for me, I’d like to tweet this post.

My best,

Frances Kuffel
- February 19, 2018 at 1:22 pm, Ted said:
  
  Thanks, Frances!
  
  It’s worth noting that the most common standard for a meaningful weight loss benefit is either:
  – A 5% greater benefit in the treatment group versus the control group,
  or
  – At least 35% of the people in the treatment group losing 5% or more of their initial body weight.
  
  This study proves that vinegar did not meet the first criterion. On the second one, it provides no data.
  
  It’s also worth noting that these standards are for weight loss after a year, because most people start re-gaining some weight after six months. The data in the vinegar study were only for 12 weeks. By the time a year rolls around, you can assume that some of the benefit will fade.
  
  Finally, using vinegar like this is not free from risks, even though Khezri study doesn’t report them. Darzi et al report that it not only causes nausea, but also has been “linked with oesophageal injury, biochemical disturbances, dental erosion and acute pancreatitis and symptoms such as acid reflux, burping/flatulence and changes in bowel habit.”
February 19, 2018 at 1:11 pm, David Stone said:

I eat fairly large salads and one tbsp of any vinegar (along with oil and seasonings) would be no problem at all, even twice a day. As a side-note, I seem to recall from a few decades ago that Paul Bragg, in his “Miracle of Fasting” book, suggested adding small amounts of apple cider vinegar to the water that he advised drinking during a (once weekly) 24-hr fast. Perhaps he was onto something–less hunger would presumably make fasting easier. The acetic acid in a tbsp of vinegar does provide a few Calories, though. Interesting substance, actually–it’s the shortest-chain fatty acid, and should be about midway between carb and fat, Calorie-wise.
February 19, 2018 at 1:35 pm, David Stone said:

Ted, an FYI about the website and not intended as a comment: after entering some text in the comment box using Chrome on my Windows 7 desktop computer, if I press the End key, then either the PgUp or PgDn key, the webpage is jerked to the left with the left edge of the comment box, along with some of its text, out of sight. I haven’t been able to find a way to recover and instead have to copy the contents (Ctrl-a, crtl-c), reload the page, then paste the contents into the new empty box.

Firefox does NOT show this behavior, btw. Go figure.

Cheers,

DS
- February 19, 2018 at 1:48 pm, Ted said:
  
  Sorry about that, David.