Yo-yo dieting, also known as “weight cycling,” describes the pattern of losing weight, regaining it and then dieting again. It’s a process that causes weight to go up and down like a yo-yo. This type of dieting is common — 10% of men and 30% of women have done it.

Negative Effects Of Yo Yo Dieting

1. Weight gain
A new study from the University of Exeter and Bristol found repeated dieting can do the opposite of what you want and ultimately lead to weight gain because your brain interprets these extreme swings in eating patterns as “short famines.” (Which is different than calculated fasts.) You can probably guess where this is going. Your body goes into survial mode and prompts the storage of fat for future shortages. This is also a common downfall for people who try to stick to super low-calorie diets. What’s more, you’re more apt to binge and overeat, so you’re never truly able to keep any weight off. You can thank evolution; animals, like birds, respond to shortages in food supply by gaining weight to stay alive. Unfortunately, the researchers say, our bodies are hardwired to follow this model.
“Surprisingly, our model predicts that the average weight gain for dieters will actually be greater than those who never diet,” leady study author Andrew Higginson said in a press release. “This happens because non-dieters learn that the food supply is reliable so there is less need for the insurance of fat stores.”

2. Psychological frustration
By depriving yourself of fuel and maxing out during workouts, your only result is burnout. Sure, you’ll see some weight loss; but that’s only due to water loss and dehydration. “When people put themselves on a diet, they often forbid themselves to eat the foods they love, but dieting is not the same as healthy eating, and this leads to a sense of deprivation, which can derail your healthy intentions,” says Rebecca Scritchfield, registered dietitian nutritionist, and health/fitness specialist. “Over time this creates the effect of yoyo weight cycling, which can take a toll on your emotional and physical well-being.

3. Gut dysfunction
That gargantuan shift from hot wing-stuffing-cocktail binges to I’m-only-going-to-eat-negative-calorie-celery benders you transition in and out of from the onset of football season to New Years is a rough one—especially for your stomach, according to a study from the University of New South Wales. And we don’t just mean when it comes to your waistline. Yoyo dieting throws off the healthy balance of gut bacteria. Usually, your gut’s home to about 100 trillion microbial cells that influence everything from metabolism to immune function to overall nutrition. But when the levels and diversity of bacteria are disrupted, gastrointestinal conditions like inflammatory bowel disease and obesity are the result.

Another study found something similar. When Israeli researchers put mice through a cycle of weight loss and gain, they found that the rodents’ systems all returned to normal but one: Their microbiomes (germ colonies) stayed in “obese” mode for six extra months, Nature reports.
It seems the little guys’ guts remembered obesity fondly, and sped up weight gain when off the diet.
The finding may lead to treatments to combat yoyo dieting. Till then, fortify your gut with plenty of probiotic (yogurt, kimchi) and prebiotic (asparagus, onion) foods.