File this under “latest diet fads that sound too good to be true.”
It’s an export from England called the “Fast Diet,” and in this case, the “fast” refers not to speed but to limiting food intake.
According to national reports, people in England are losing weight by eating what they normally eat for five days and fasting for two days. On those two days of fasting, according to the diet’s protocol, you can still eat, but only about 25 percent of the calories you’d normally consume.
Those fasting calories should come, ideally, from protein, fruits and vegetables.
A woman who spoke with ABC News said she’d lost 36 pounds over seven months on the Fast Diet, and her appetite has been quelled.
But is the diet safe?
“Safe diet plans should include items from every food group and provide at least 1,200 calories per day,” says Mankato Clinic dietitian Erin Gonzalez. “Diets that forbid entire sections of food groups or suggest very low-calorie intake are dangerous and unhealthy — and will not help with long-term weight loss.”
Having said that, Gonzalez said she understands how the diet can make sense. By restricting calories below 1,200 for two days of the week, it reduces the body’s tendency to go into starvation mode, which would slow down the body’s metabolism to conserve energy and cause reduced weight loss.
“The idea of only reducing calories a few days out of the week allows for fewer calories overall without the body recognizing a pattern, resulting in weight loss,” Gonzalez said.
Theresa Pratt, a dietitian for Mayo Clinic Health System, said it’s a good idea to see the bigger picture when considering a diet like this.
“People who use fasting as a fat loss technique usually believe that since food is to blame for excessive weight gain, then avoiding food is the best shortcut to a leaner body,” Pratt said. “While this might seem to make sense, it overlooks the fundamental principle that the body needs food to properly function. This means that depriving the body of food through fasting is a sure way of negatively affecting the proper functioning of your body.”
Long-term weight loss can only be achieved and sustained through meaningful lifestyle changes, they said.
“People should always be cautious of any diet or meal plan that restricts certain foods, suggests calorie levels below recommended intakes and claims fast results,” Gonzalez said. “I challenge my patients to ask themselves not what they are eating but why.”
Whether or not fasting is healthy, Gonzalez said, is a hotly debated topic among medical professionals.
Most experts say fasting for weight loss is not healthy, Gonzalez said, and is not a good answer for an overall healthful lifestyle. It can also be dangerous if taken to an extreme. It can lead to nutrient deficiencies and be problematic for patients with liver or kidney problems, compromised immune systems, or for people taking certain medications.
Added Pratt, “This appears to be the next fad diet. These diets become very popular quickly and may fall out of favor just as quickly. Some susceptible people might develop poor eating habits while on the diet, and engage in starvation, binging or both. This diet doesn’t teach people how to make healthy lifestyle choices that can be sustainable. Keep in mind that you can out eat any diet plan if you were to splurge on the five non-fasting days.”