In the ever-evolving quest to live longer and healthier, we know that diet plays a key role. In recent years, scientists have also focused on the potential of intermittent starvation – a diet that depends when you eat, no What you eat.
However, new research suggests that it may not achieve what some intermittent hasteers look for when they perceive it as a diet.
Growing evidence, mainly in animals and relatively small groups of people, suggests that periodic fasting (sometimes called time-limited eating) can improve metabolic function, prevent certain diseases, and even prolong life. Based on these findings, intermittent fasting ̵
Periodic fasting is also charged as a simple weight loss strategy: No calorie counting, complicated recipes or cutting out certain food groups.
However, in a recent randomized clinical trial, one of the most rigorous dietary studies to date, researchers followed 116 obese and overweight people for three months to see if scientific evidence matched the hip.
The team, for their part, found that time-limited eating or intermittent fasting did not help people lose much more weight than just eating three times a day. Instead, it had an involuntary side effect: loss of lean muscle.
Can periodic fasting actually help you lose weight?
Ethan Weiss is one of the study’s co-authors and a cardiologist at the University of California, San Francisco. His team published its findings in the journal on Monday Internal medicine of JAMA.
Prior to this work, Weiss practiced time-limited nutrition for the past seven years. After analyzing these results, he stopped.
“No matter how you look at it, the time-limited diet has led to very modest weight loss [about .2 pounds per week over 12 weeks on average], “Weiss tells Back. “It offered no other metabolic advantage. And then the alarm signal about the loss of lean mass appeared.”
Victoria Catenacci, endocrinologist and metabolic expert at the University of Colorado, Anschutz Center for Health and Wales, says the study is “well done,” but says factors such as window feeding time, lack of behavioral support and reduced physical activity in the fasting group may have affected the results. Catenachi did not participate in the study.
“This well-designed study shows that late time-limiting eating without behavioral support alone does not lead to clinically significant weight loss for 12 weeks,” says Catenacci. Back. She notes that this study is another reminder of the critical need for “a rigorous assessment of weight loss interventions, such as time-limited nutrition, before recommending them to the general public.”
Katenacci also acknowledges that there are still many open questions regarding this diet, arguing that the study does not “close the door to time-limited nutrition as a weight loss intervention” or as an intervention that can cause other positive effects. effects, including longevity.
What the study examines – To determine how intermittent fasting or time-limited eating affects weight and metabolism, Weiss and his team recruited a group of 116 people who were classified as overweight or obese.
The researchers divided the group into two diets. Half practice a limited daily diet – eating all their meals between noon and 20:00. Then fasting for 16 hours. Only low-calorie drinks were allowed outside the dining window.
The other half ate three meals a day, including snacks. Neither group was given instructions on what and how much to eat during the day. They are also not instructed to train or abstain from exercise.
For three months, the researchers tracked both group weight and metabolic results using a mobile app, studies and a Bluetooth scale. Each participant is weighed daily in the morning before eating or drinking.
Results and explanation – The researchers predict that the group on an empty stomach will lose weight more than the group with three meals a day. But for 12 weeks, there was no greater weight loss with a time-limited diet compared to the sequential diet group.
There were also no significant observed differences in fat mass, fasting insulin, blood sugar, HbA1C or blood lipids between the two groups.
“… there is nothing magical for the window itself with a time-limited meal for short-term weight loss. “
“The minimal weight loss suggests that they have not achieved a significant energy deficit,” says Catenachi. “I think that suggests there’s nothing magical in the window itself with a time-limited meal for short-term weight loss.”
During the study, participants in the group on an empty stomach lost about three and a half kilograms. But most of the weight lost was not fat.
Crucially, it was lean mass, including muscle mass. Usually about 20 to 30 percent of total weight loss is net weight. In this study, the share of net weight loss was 65 percent.
“You don’t want to lose lean mass. You want to lose fat,” Weiss said. “Here we found that two-thirds of weight loss comes from pure mass.”
There are a number of potential factors that cause participants to lose weight on an empty stomach, one of which is that participants may not have eaten enough protein or received enough physical activity. On average, participants walked on an empty stomach with about 2,500 fewer steps per day, a change in activity that could contribute to their unchanged weight and decreasing net weight.
It is also possible that fasting later in the day does not limit energy intake, leading to weight loss.
“Preclinical data suggest that the window of time-limited nutrition may have greater metabolic benefits and in practice early [eating] a window may be more likely to lead to greater calorie restriction, as most people currently consume most of their calories later in the day and evening, ”Katenachi explains.
She recommends that strict attempts be made in the future to evaluate other periodic nuances on an empty stomach, such as eating earlier in the day or combining it with a low-calorie diet.
What follows for periodic fasting – Following the publication, the study by Weiss and his team sparked an immediate discussion, with experts evaluating the results on social media. Some argue that study participants are not fast enough or early enough in the day to see a real benefit. Others say that to see the results of weight loss, the diet should be combined with other diets.
In the end, the test shows what a lot of research on nutrition and exercise does: that there is no unique solution or magic strategy for weight loss and a long healthy life.
“It’s just one mode, but it emphasizes how easy it is to think something works when it doesn’t work,” Weiss says. “Or maybe more precisely that something works.”
The findings certainly do not support that there will be any major effect of starvation, Weiss added.
“Longevity? Who the hell knows,” Weiss said. “Weight and metabolic endpoints are hard enough!”
Meanwhile, if people want to include fasting in their daily lives, experts say that fasting is not an excuse to completely eliminate healthy eating.
“As I tell my patients, the point is not to eat what you can during [eating] window, but to use the window as a strategy to reduce your total daily calorie intake, “says Catenachi. , is an effective weight loss strategy. “
IMPORTANCE: The efficacy and safety of time-limited nutrition have not been studied in large randomized clinical trials.
OBJECTIVE: To determine the effect of 16: 8-hour restricted diet on markers of weight loss and metabolism.
INTERVENTIONS: Participants were randomized to have the sequential meal setting (CMT) group instructed to eat 3 structured meals per day and the time-limited meal group (TRE) to be instructed to eat optionally from 12:00 to 20:00 and completely refrain from eating calories from 20:00 to 12:00 the next day.
DESIGN, ESTABLISHMENT, AND PARTICIPANTS: This 12-week randomized clinical trial involving men and women 18 to 64 years of age with a body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) of 27 to 43 was conducted on a personalized mobile training application. Participants received a Bluetooth scale. Participants lived throughout the United States, with a subgroup of 50 participants living near San Francisco, California, who underwent personal testing.
MAIN RESULTS AND MEASURES: The main result is weight loss. Secondary outcomes of the personal cohort included changes in weight, fat mass, lean mass, fasting insulin, fasting glucose, hemoglobin A1c levels, predicted energy intake, total energy expenditure, and resting energy expenditure.
RESULTS: A total of 116 participants (average [SD] age, 46.5 [10.5] years; 70 [60.3%] men) were included in the study. There was a significant weight loss in TRE (-0.94 kg; 95% CI, -1.68 to -0.20; P = .01), but there was no significant change in the CMT group (-0.68 kg; 95% CI, -1.41 to 0.05, P = .07) or between groups (-0.26 kg; 95% CI, -1.30 to 0.78; P = .63). In the personal cohort (n = 25 TRE, n = 25 CMT) there was a significant weight loss in the TRE group (-1.70 kg; 95% CI, -2.56 to -0.83; P <.001). There was also a significant difference in the appendicular net mass index between the groups (-0.16 kg / m2; 95% CI, -0.27 to -0.05; P = .005). There were no significant changes in any of the other secondary outcomes within or between groups. There are no differences in the estimated energy intake between the groups.
CONCLUSIONS AND RATIO A limited time diet, in the absence of other interventions, is no more effective in losing weight than eating throughout the day.