The participants, who adhered to the diet the strictest, reported the most weight loss, but even those who followed a less rigid intermittent fasting regimen lost weight.
Research on intermittent fasting has been mixed. While some studies have argued intermittent fasting isnâ€™t a significant driver of weight loss, the bulk of research suggests the eating pattern can have a wide range of health benefits on conditions like obesity, cardiovascular disease, diabetes, cancers, and neurological disorders.
Intermittent fasting appears to facilitate weight loss
The Queen Mary University of London asked 50 people with obesity to practice intermittent fasting for 12 weeks.
Participants were asked to follow a time-restricted diet where they fasted for 16 hours and had all their meals within an 8-hour window.
The researchers conducted a weekly phone survey to monitor the participantsâ€™ progress. The participants were weighed after 6 weeks and again at 12 weeks.
Sixty percent of the participants were still following the restricted diet plans 3 months in. On average they lost about 7 pounds, which amounted to at least 5 percent of their body weights.
Those who loosely followed the fasting regimen also lost weight.
This study is small, though. Rigorous research with more participants is needed to better understand if and how intermittent fasting leads to weight loss.
Why intermittent fasting can lead to weight loss
The most common intermittent fasting plan is the 16: 8 diet, which requires people to fast for 16 hours then eat only within a specified 8-hour window.
Intermittent fasting has become increasingly popular in recent years, but the research has been mixed on whether intermittent fasting can cause meaningful weight loss.
Dr. Artur Viana, the clinical director of Yale Medicineâ€™s Metabolic Health and Weight Loss Program and an associate professor of digestive diseases at Yale University, said weight loss likely happens since people practicing time- restricted eating tend to consume fewer calories overall.
â€œIt is unlikely that someone will overcome the calories skipped during the 16 hours of fasting in those 8 hours theyâ€™re allowed to eat,â€ Viana said.
Dr. John Morton, a bariatric surgeon at Yale Medicine and vice chair of surgical quality for Yale School of Medicine, said intermittent fasting also reduces nighttime eating.
â€œOne thing that we are sure of is that when you eat late at night, it does increase your risk of gaining weight,â€ Morton said.
Because the metabolism slows down at night, itâ€™s harder to burn calories, Morton said.
Some research suggests intermittent fasting can also enhance metabolism.
â€œSmall studies have suggested that time-restricted eating (TRE) may counteract metabolic adaptation after weight loss (a mechanism that leads to weight regain), favorably affect body composition towards decreased fat mass, decrease hunger, and increase satiety,â€ Viana said, but adding that this has yet to be confirmed by larger studies.
Dr. Mitchell Roslin, the chief of obesity surgery at Lenox Hill Hospital in New York City, said evidence shows fasting causes insulin levels to drop.
â€œTo maintain blood glucose, the liver will secrete glucose reducing short-term energy stores and in theory promote fat burning,â€ Roslin said.
What the experts think of intermittent fasting
Many people struggle with sticking to intermittent fasting in the long term.
â€œSome people may find it difficult to fast for 16 hours, and this may lead to poor adherence and hence absence of weight loss,â€ Viana said.
When it comes to intermittent fasting, adherence is â€œvery important to a successful weight loss intervention and key to avoiding weight regain,â€ Viana said.
Additionally, itâ€™s crucial to eat the right foods.
â€œThe problem with the patients I see is that eating very unhealthy processed foods in a restricted time will not lead to significant improvement,â€ Roslin said.
While time-restricted eating may be beneficial, what you eat still matters.
When it comes to weight loss, the most important thing is to eat a healthy diet with lean protein, whole grains, and vegetables, said Viana.
Overall, though, intermittent fasting is thought to be safe for most people.
However, people with diabetes should avoid time-restricted eating as it can increase the risk of low blood sugar, according to Morton.
Viana recommends intermittent fasting to patients, but emphasizes that interventions for weight loss arenâ€™t one-size-fits-all.
â€œAn effective strategy is one that can be maintained long term,â€ Viana said. â€œIf for someone that strategy is time-restricted eating, or intermittent fasting, then thatâ€™s the way to go.â€
More research is needed to clarify whether intermittent fasting is a more effective weight loss strategy compared to other types of diets.
The biggest question, said Morton, is how durable are the results achieved through intermittent fasting.
â€œOne truism in dietary approaches is the more complex and difficult the diet, the harder it is to stick to it,â€ Morton said.
The bottom line
Intermittent fasting can help reduce overall calorie intake, especially nighttime eating, which may help people lose weight.
Some experts suspect it could enhance metabolism and boost fat burning. More research is needed to explore the impact intermittent fasting has on our health and how it can be used for weight loss.
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