Millions of people believe
intermittent fasting can help them lose weight. But a new study may dash those hopes.
A team of researchers at the University of California, San Francisco, conducted a clinical trial to test the diet and came to a startling conclusion: There is "no evidence" that intermittent fasting helps people lose weight.
As part of the 12- week trial, some participants were asked to skip eating in the morning, and to instead eat at random times within a strict eight-hour window each day. Those participants lost an average of 2 pounds during the trial.
However, other participants who were allowed to snack and eat meals at normal times lost an average of 1.5 pounds.
Researchers determined that the difference in weight loss between the two groups was not statistically significant.
The study results do not surprise Angela Lemond, a Plano, Texas-based registered dietitian nutritionist and founder of
Lemond Nutrition.
"There is no ‘one size fits all’ for weight loss, and that includes intermittent fasting," says Lemond, who was not involved with the clinical trial.
Intermittent fasting benefits
Intermittent fasting is a dietary regimen where people go hours - - or even days -- eating little to no food. Those who adhere to this plan typically are careful not to deprive themselves of essential nutrients.
There are many different methods of intermittent fasting, including:
- Only eating within time restrictions, such as during a six-hour or eight-hour window each day
- Fasting on alternate days
- Fasting on a "5:2" schedule that involves fasting on two days each week
Intermittent fasting might has been linked to several health benefits. Earlier this year, a review of the research published in the New England Journal of Medicine concluded that intermittent fasting might lead to improvements in a host of health conditions, including:
- Cancer
- Cardiovascular disease
- Neurological disorders
- Obesity
The potential health benefits of intermittent fasting appear to be related to metabolic switching, according to the authors of the review published in the New England Journal of Medicine. Metabolic switching is a process where fasting causes the body to alter its source of energy from glucose stored in the liver to ketones stored in fat.
As ketones rush into the bloodstream, they start a process that boosts the body's ability to fight oxidative and metabolic stress, and also help remove or repair damaged molecules.
The result can be improved glucose regulation, greater resistance to stress and lowered levels of
inflammation, according to the findings published in the journal.
Despite those findings, it is worth noting that the researchers who conducted the University of California trial did not find that intermittent fasting improved health markers such as fasting insulin or glucose levels.
Should you try intermittent fasting?
Whatever the health benefits of intermittent fasting may be, the University of California trial seems to throw cold water on the main reason people fast intermittently – the hope of losing weight.
For some people, the discipline of trying to stick to a regimen of intermittent fasting may help them avoid overeating, Lemond says.
“For those wanting to shed extra pounds, intermittent fasting may stop things like mindless eating in the evenings while watching TV,” she says.
However, as a general rule, Lemond tries to steer clients trying to lose weight away from the quick-fix notion of intermittent fasting and toward more lasting solutions.
For example, she notes that many people who undereat during the day make up for those lost calories -- and then some -- in the evenings.
“We work on spreading out food intake throughout the day, so there is less of a desire to eat a large quantity of food at any one time,” Lemond says.
As an added bonus, Lemond says people who eat regularly throughout the day have a tendency to choose higher-quality foods.
“Our practice works off the premise of eating quality foods when you are truly hungry,” Lemond says. “We also want to focus on
building and maintaining muscle.”
