I’ve written about nutritional myths that have made people from nearly every dietary tribe at least a little annoyed with me. But today? I’m coming for one of my final dietary bosses.
Today’s Moment of Science… The Myth and Meaning of Starvation Mode.
I’ve been overweight most of my life. I was told, and subsequently believed, plenty of wrong things that were supposed to be the key to a slimmed down physique and happiness, which were marketed as one in the same. First it was cutting fat. Then overall calories. Then carbs. Then it was avoiding an ever growing litany of seemingly more arbitrary foods of various nutritional densities and compositions because random studies– or maybe just an email forward from your aunt’s hairdresser– had linked them to weight gain.
Growing up a fat chick in the nineties was rough, my friends.
One of many ideas with an identity crisis in the world of nutrition is starvation mode. The term is sometimes applied to the idea that you can eat so few calories that your body rebels and packs away every crumb it can for what your tuchus suspects to be an impending famine. It’s not clear what level of food intake is supposed to cause this effect, but at some caloric level that should all but guarantee weight loss, the body instead panics and goes “YOU’RE NOT THE BOSS OF ME.” At which point the scale won’t budge, or the horror, creeps up instead.
I may have survived on Diet Coke and the vague memory of carbs more than once in my life only to end up a size bigger afterwards, so I understand why this feels deeply true. I’ve accepted most of that was from being super dedicated to This Diet That Will Work on Monday then being intensely goddamn “fuck it” by Thursday afternoon.
The dieting-yourself-bigger idea is one of many common misconceptions with a ‘starvation mode’ label slapped on it. Ditto the idea that any diet causes the metabolism to drop. Or it’s a survival mechanism to keep on calories that only occurs with malnutrition and, you know, actual starvation.
Though studies have suggested there are metabolic hijinks at play during weight loss, it’s complicated. To better understand this, let’s look at two things: first, the effects of caloric restriction on weight.
A sufficient cut in calories will lead to fat loss for just about anyone. Before we go even a smidge further, I see you raising your hand to ask Mrs. Auntie SciBabe about thyroid issues, slow metabolic rates, PCOS, medications, and idk like four other things. A “sufficient” cut is gonna vary based on many factors. Point being that there exists a caloric level that will lead to a gain or drop in weight for all critters, great and small.
Second, and more importantly, let’s examine the effects of caloric restriction on metabolism. Because there are a few balls in the air here, and I would like to tickle them all.
It surprises some people to find out that weight loss- even if heroic levels of muscle are packed on- causes a drop in resting metabolic rate (RMR). This is the amount of calories burned daily from not doing a goddamn thing. It’s definitely one of the reasons I gained weight back over the years. Old habits die hard and, as much as cutting down temporarily was doable, adjusting to a smaller body that needs fewer calories is a fucker.
But, that part isn’t starvation mode.
There’s this weird quirk that RMR after weight loss can be a bit lower than in people of a comparable but long-term stable weight. This is referred to as metabolic adaptation, and that’s… probably starvation mode. I think. That’s the thing that somehow turned into the myth of “dieting will ruin your metabolism and makes you fat.”
Two studies that come up most frequently when discussing this involve the Minnesota Starvation Experiment and the show The Biggest Loser which, fuck Jillian Michaels, was a televised starvation experiment. In both cases, subjects dropped weight drastically and suffered depressed metabolisms for years afterwards, far beyond what their weight loss should have caused.
But it’s not clear how consistent the effect is or what, if any, bearing it might have on maintaining weight loss.
In some less flashy studies, people have been shown to experience a depressed RMR while in a caloric deficit and actively losing weight, yes. Once they’d been at a stable weight for a while though, their daily-burn-while-doing-fuckall rate adjusted itself to a normal range for their new weight. One current hypothesis for why this happens attributes it not to a loss of muscle, but fat. Production and management of some hormones vital to the metabolism go all cattywampus after weight loss because body fat plays a vital part in this.
While metabolic rate can dip right after weight loss, newer studies suggest it’s a temporary or much smaller effect than previously described. That said, if you’re going to try to lose weight, the studies showing long term metabolic bedshitting involved, uh, literal fucking starvation. So before you wreck yourself on a caloric deficit meant for a lightly bloated teacup chihuahua, check with your doctor and a registered dietitian to discuss what’s healthy for you.
This has been your Moment of Science, already planning to ignore the hate mail.
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