Another meal, another medical mystery…
As I savoured the dying moments of the summer bank holiday, I was relishing the last few mouthfuls of a marvellous and hearty meaty meal. Then as the sun started to set, that dreaded line finally came: “Hey, I’ve got a question for your blog!”
Now something of a running joke, the question has become an excuse for friends to ask me all manner of interesting, amusing and distasteful questions. This one was better than most – “Why do we get meat sweats?”
Having indulged in liberal servings of steak, chicken and tuna – all cooked on a Raclette (a quirky Swiss Fondue-BBQ hybrid plate invention) – we knew what would likely come next: Hours spent lying in bed overheating and sweating profusely – this seems to be the punishment for such protein gluttony. But why? What causes the dreaded ‘meat sweat’?
What is a Meat Sweat?
Vegetarians will probably never have to undergo the unpleasant duvet-drenching ‘meat sweat’ experience. The Urban Dictionary sums up this bizarre ordeal pretty neatly:
“To consume an obscene amount of meat resulting in perfuse sweating.” Urban Dictionary
What causes Meat Sweats? Are they Real?
Meat sweat deniers argue that the burger-related perspiration problem has never been scientifically proven. They are correct – an article on ‘Meat Sweats’ won’t ever get published in a medical journal. However, something about ‘Protein-induced thermogenesis’ will… (clearly)
The Science of Meat Sweats
If I had a TV show, it wouldn’t feature anything like Brian Cox’s starry-eyed ‘Wonders of the Universe’ spiel – Oh no, instead I’d get all loquacious about the marvels of the human body. Because that skin-covered biological machine you’re sitting in is a mighty impressive bit of kit. But like any machine, the human body isn’t perfect. Take digestion: when you eat food – some of it gets wasted. When you troughed through that Big Mac at lunchtime, not all of those 500 calories actually made it into your body. A significant portion of its calorific content was lost (excluding what you spill down your top, of course).
Have you ever noticed how you feel warmer after a meal? In the process of absorbing energy and nutrients from food, your body ends up using some of that energy – as heat. Put another way: there is an energy cost to breaking down food. This cost in energy terms means you get warmer (just like doing exercise). So, about 60 calories of that Big Mac you just ate has been lost as heat in what’s called the ‘thermic effect’.
The Thermogenic effect of ProteinEat enough of anything and you’ll you’ll start to sweat (well, perhaps not celery), such is the powerful thermic effect of eating food. (Confusingly, it’s also called ‘thermogenesis’ or the ‘thermogenic effect’ – depending on who is writing). For reasons mostly unknown – some types of food have a larger thermogenic effect than others, making the body produce more heat in the minutes and hours after eating it.
Starchy foods (like bread) give up about 10% of their calories in heat after meal time. The champions of the thermogenic league table are protein-based foods (meats, etc) – giving up at least 25% of their energy content as heat – sometimes more. This means that from every four bites of your pricey venison steak, one bite will be radiated out of you as pure heat!
Some say that the body-heating thermogenic effects of high-protein foods are why fad diets such as the Atkins have been so successful. The scientific community have yet to conclude whether this is actually the case.
I know that one thing’s for sure: if heating prices soar this winter, one way to offset the bills is with a mixed grill before bed…
Thanks for reading – comments and feedback are warmly welcomed!
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DISCLAIMER: All of the writing in ‘Doctor Stu’s Science Blog’ are intended for educational and entertainment purposes only. Please do not base your healthcare decisions on the information contained in this blog: Always see your GP first!INTERESTED IN THIS SORT OF STUFF? I’ve been part of a team that has just launched a new (free) bi-monthly magazine which aims to deliver more of the same. It all started on 1st June 2011 – Check it out here!
Halton TL, & Hu FB (2004). The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. Journal of the American College of Nutrition, 23 (5), 373-85 PMID: 15466943
Westerterp-Plantenga, M., Nieuwenhuizen, A., Tomé, D., Soenen, S., & Westerterp, K. (2009). Dietary Protein, Weight Loss, and Weight Maintenance Annual Review of Nutrition, 29 (1), 21-41 DOI: 10.1146/annurev-nutr-080508-141056