Monosodium glutamate (MSG) is a flavour enhancer used liberally in processed foods and Asian cuisine. While MSG is a permitted ingredient in the food supply, there have in the past been questions asked about its potential role in weight gain and obesity. In 2008, I wrote a post about research linking MSG with increased body weight. This association was found even when ‘confounders’ such as food intake and activity levels were taken into account.
A similar piece of research surfaced recently – published in the American Journal of Clinical Nutrition [1]. The relationship between MSG intakes and body mass index (BMI) was assessed in more than 10,000 Chinese adults over an average of 5½ years.
The results showed that higher MSG levels were associated with higher BMI (and greater risk of being overweight). Again, the association remained even after factors such as food intake and activity levels were taken into consideration.
If you believe that weight is only determined by caloric balance, then these results will not make sense. The authors of the study don’t make that mistake, though, and go on to discuss the potential mechanisms behind their findings.
In particular, they focus on the impact glutamate can have on a part of the brain known as the hypothalamus. Although small in size, the hypothalamus has a regulatory role in key processes including metabolism and hunger. A few weeks ago, one of my blogs focused on the role that the hormone leptin has in body weight regulation through its impact on the hypothalamus. Leptin suppresses appetite and stimulates the metabolism. However, if it doesn’t do its job properly (‘leptin resistance’), this does not bode well for maintenance of a healthy body weight.
As the authors of the MSG paper point out, glutamate has the ability to damage the hypothalamus, and has the ability to cause leptin resistance. This mechanism alone, and its potential impact on metabolism, could explain how MSG might predispose to obesity, even when food intake and activity levels are taken into account.
If you want to avoid MSG, ensure your diet is made ostensibly from natural, unprocessed foods. And avoid soy sauce and other condiments likely to be laced with MSG including gravy mixes and concentrates.
References:
1. He K, et al. Consumption of monosodium glutamate in relation to incidence of overweight in Chinese adults: China Health and Nutrition Survey (CHNS). Am J Clin Nutr 2011;93(6):1328-36.
Dr. Briffa,
I’m a loyal reader with a pet peeve. please read this:
http://emmanuelpress.com/article/words-matter-when-a-blog-is-not-a-blog/
Are there forms of soy sauce without MSG in? I hope so I like my stir frys
I realised about thirty years ago that I always felt awful the morning after eating chinese food, but it was some time before I discovered that it was MSG that was causing the trouble. My eyes were swollen and itchy, my rings felt tight and I’d have a crashing headache. This wore off after a couple of hours and a few glasses of water. Since then I’ve tried to avoid MSG as much as possible, which means reading labels on things like crips, snacks, tinned soup and processed food in general. When I do eat something with MSG by accident, usually when eating out, I get the same symptoms again in varying degrees.
I remember reading an article years ago about a mother who had to go away on a trip for three weeks, leaving her two children with their father. When she came home she noticed both the children had unhealthy-looking puffy faces. She discovered Dad had been feeding the children mainly on take-aways and processed food. When she put them back on a fresh food diet the puffiness gradually went away. She did some research and came to the conclusion that MSG was the culprit.
It’s hard to identify food items that contain MSG. Quite often it is listed as ‘natural flavor’.
Dr. Briffa, I’ve been following you for some time. As a wellness and weight loss management coach I’ve found that your lucid explanations and logical analysis of scientific findings help me communicate with my clients. Slow/low carb is the way to go. Although I generally recommend skimping on the salt as well, I was not aware of the link between MSG and weight. So, that’s another great addition to what I can offer my clients. Thanks so much.
I thought the puffiness and the weight gain (if any) from a lot of msg would be from the ‘sodium’ part of ‘monosodium glutamate.’
I also thought the original loss of weight on low-carb diets came from loss of water weight.
Doesn’t actually matter to me. I consider both to be short-term dietary intakes, anyway.
Kate
Got any data on this?
I have kept away from MSG since I found it caused aches in my joints. Mary
Glutamate, which if necessary can be easily oxidized – giving the the mole, until about 16 moles of ATP netto.
I don’t have website. I am a male nurse from Philippines working here in Sharjah, UAE. I observed Monosodium Glutamate can kill dogs.Get loaf of bread, fish,or whatever dogs eat, and mix it with monosodium glutamate and let your dogs eat it. You will observe your dog will die unless you will cure them. I think monosodium glutamate is not only poison to dogs but also to humans.
Hi Dr Briffa,
My husband and I were just discussing this effect of MSG and I found your article while researching it online.
We have been on a low carb diet for some time now – I have lost 88 pounds eating like this, my husband about 26; but we have found that if we eat a Chinese takeaway that the weight loss just STOPS for about 4 days. Recently we ordered a duck – nothing else – no noodles or veggies – and the same thing happened. No weight loss for 4 days.
Thanks for posting this article – its a very helpful addition to my knowledge base, and scientifically backs up our hunch that the MSG had some effect above and beyond making food yummier so that you eat more.
I should like to add to Kate: 88 pounds is a LOT of water
Low carb engages your metabolism in a completely different way. I have a page on my Blog dedicated to low carb weightloss – called “The High Fat Diet” – its up the top. Do check it out – I have listed all the links you need to have a look at the science behind a low carb, high fat diet. I also have photos, if you think I’m pulling your chain 
Its all true, and if I hadn’t spent about 6 months researching it (and I a Professional Researcher) I would not have believed it myself !!
All The Best !
Molly
Hi Dr Briffa,
Sorry ! *blush* I’ve just read the rest of your site and have realised that you’re advocating a low carb high fat diet too !! I’m so used to “advocating” for the diet I don’t always stop to check where I’m advocating it. Or maybe that should be “evangelising”
I shall buy your book and add you to my list of links !
Cheers !
Molly
Molly