Crash dieting leaves you with more belly fat and weaker muscles, a new study has warned.
A study performed on rats found limiting the number of calories per day not only increased the circumference of the rats' waists but also thinned out their muscles.
Even more troubling: a hormone known to increase blood pressure became hyperactive in the rats on the reduced-calorie diet.
The team, led by Georgetown University in Washington, DC, warn that the two combined - increased blood pressure and belly fat together - could pave they way to dangerous long-term health risks, such as diabetes and heart disease, for past crash dieters.
For the study, the team split female rats into two groups - one where calories would be reduced and one where the diet would remain the same.
The reduced group had their calories slashed by 60 percent, the equivalent of reducing a diet in humans from 2,000 calories to 800 calories.
After three days of being on the reduced-calorie diet, the rats' weights were lowered, but the diet also caused cycling - similar to a human's menstrual cycle - to stop.
In addition, a number of metabolic functions decreased including blood pressure, heart rate and kidney function.
When the rats resumed a normal diet, cycling was restored and both heart rate and body weight increased.
But the researchers found that three months after the reduced-calorie diet, the rats had more belly fat than rats that ate a normal diet.
'Even more troubling was the finding that angiotensin II, a hormone in the body, was more potent at increasing blood pressure in the rats that were on the reduced-calorie diet,' said Dr Aline de Souza of the Department of Medicine at Georgetown University Medical Center.
Additionally, it stimulates the production of other hormones in the body that cause the body to retain salt and water.
Dr de Souza said that this increased blood pressure, when coupled with increased belly fat, could pose long-term health risks for people who have crash-dieted in the past.
Several previous studies have found that crash dieting can wreak havoc on the body both immediately and in the long run.
Because your body is unsure of when you will feed it again, it conserves as much energy as possible so you burn fewer calories throughout the day.
Additionally, although your body burns through fat stores first, it will then turn to lean tissue in the form of your muscles.
A 2014 study at Maastricht University in the Netherlands put one group of subjects on a 500-calories-per-day diet and the other on a 1,250-calories-per-day diet.
At the end of the study period, the 500-calorie group lost 3.5 pounds of muscle mass, but the 1,250-calorie group lost just 1.3 pounds of muscle.
Following a crash diet, the body then works to first rebuild fast stores before muscles, meaning any fat lost while dieting will come back first.
The findings of the new study are being presented today at the American Physiological Society's annual Cardiovascular, Renal & Metabolic Diseases: Sex-Specific Implications conference in Knoxville, Tennessee.