For some people, shifting their meals into a 10-hour window melts away kilos and food cravings. For others, it ends in frustration and dinner-table battles. A new study in Denmark reveals what separates success from struggle – and why even small tweaks can make the difference.
Counting calories can lead to short-term weight loss but is not sustainable for most people in the long term. About four of five regain the weight within a year.
“After two or three months, most often people are not able to do it in everyday life. It gets too difficult and too technical. People do not want to count and weigh everything they eat,” explains Natasja Bjerre, a researcher at Steno Diabetes Center Copenhagen who studies how people respond to various health interventions such as diet and exercise changes.
Co-author Jonas Salling Quist, researcher at Steno Diabetes Center Copenhagen, explains: “Healthcare providers are trying to expand the toolbox of weight-management strategies, including for people with prediabetes. Time-restricted eating is one such approach, focusing on when you eat rather than what you eat.”
“Time-restricted eating sounds so simple: you just have to change when you eat and not what you eat,” Bjerre says. But do not underestimate the impact of changing mealtimes, she cautions. These schedule shifts can disrupt the social rituals surrounding food, and not everyone finds adapting to a new rhythm worthwhile.
In an article in Nutrition Bulletin, Bjerre, Quist and a team of researchers identify several factors that seem to distinguish people who succeed with time-restricted eating from those who struggle.
“Time-restricted eating is not for everyone,” Quist says. “It is never one size fits all, and eating and drinking in everyday life is so much more than just consuming calories.”
Putting the fasting idea to the test
To understand how time-restricted eating works for people with different lifestyles and attitudes, Bjerre and her team interviewed 20 people who participated in a clinical trial on time-restricted eating as a weight-loss strategy for people with overweight or obesity.
The participants, aged 30 to 70 years, agreed to eat and drink only within a 10-hour window each day – for example from 10:00 to 20:00 – without changing what or how much they ate. On average, they lost about 3 kg during the trial, but the results varied widely depending on how well they managed to stick to the routine.
The researchers interviewed participants three times: once before they began to learn about their expectations and motivations; at the end of the intervention phase, when participants had completed three months of strict time-restricted eating; and a follow-up round three months later to see who kept going. About half the participants were still following some form of time-restricted eating at that point – mostly those who had made it fit naturally into their daily rhythm.
Then, Bjerre analysed their feedback to see what set apart the people who lost weight on time-restricted eating and ultimately integrated it into their daily lives long term.
The tricky puzzle of fitting time-restricted eating into real life
The choice of where to place the eating window can make or break your time-restricted eating experience, Bjerre found. Giving priority to dinner over breakfast seems to be a winning strategy.
“The ones who had the most success thought about ‘how can I place it so I can always eat dinner with my family," Quist notes. Starting at 7:00 might sound normal, but it means your last bite has to be at 17:00 – hours before most families sit down to dinner –which “is not sustainable” for most people, Bjerre explains.
Skipping breakfast or delaying it until about 10:00 helped to preserve dinnertime rituals. “You can sit around the table and be a part of breakfast without eating, but dinner is such a social part of everyday life.”
Some participants with extremely flexible schedules – including people who were retired, unemployed or worked from home – thought it would be easy for them to adapt to time-restricted eating since they had fewer fixed points in their daily routine.
“But it was actually some of those who found it most difficult,” Bjerre says. “Suddenly they have structured ways of eating, which interfered with all the everyday life activities.”
“In contrast, people who already had a very structured everyday life also found it quite challenging to keep this eating window.”
“No, no, no”: the social side of time-restricted eating
Since mealtimes are a team sport, time-restricted eating has to be, too. The rest of the household does not necessarily have to eat time restricted, but their support is “essential”, Bjerre says. Playing schedule tug-of-war with loved ones every day can be mentally and emotionally taxing and make time-restricted eating less sustainable, Bjerre found.
“If your partner or family do not buy in, you cannot sustain time-restricted eating in the long term,” Bjerre says. Participants who reported friction with family members or friends who pressured them to relax their eating windows lost less weight and were less likely to stick with time-restricted eating after the clinical trial ended.
Social gatherings outside the home are especially challenging, Bjerre learned. Turning down everything the host of a party or gathering offers can be awkward. “People found it frustrating to keep saying ‘No, thank you, no, no, no,’” she adds.
Some people found these micro-confrontations about food so uncomfortable that they opted out of social gatherings altogether. “They took it to extremes and left a birthday party or other event when the eating window stopped,” Bjerre says. “Again, in the long term, time-restricted eating may not be sustainable if you cannot attend parties.”
Rethinking time-restricted eating: mindset matters more than perfection
Bjerre hopes that her findings will help healthcare providers understand what people find most challenging about time-restricted eating – and perhaps identify tweaks to the system to make it more sustainable.
“We need to put a little more flexibility into the concept,” Quist explains. For example, allowing calorie-free beverages – such as herbal tea or zero-sugar sodas – outside the eating window could make participating in social gatherings easier without undermining the benefits of time-restricted eating.
Bjerre found that what people hoped to gain from time-restricted eating affected their success. Participants whose main goal was major weight loss were more likely to get discouraged, whereas people who concentrated on the health benefits and day-to-day improvements in the quality of life found time-restricted eating more tolerable and more rewarding.
“Some people said they could actually feel that their blood sugar was much more stable,” Bjerre says – and for many people, this aligned with their blood tests, which showed fewer big swings in glucose across the day.
Other people found that time-restricted eating quieted the constant background chatter about food – those nagging thoughts about snacks or mild hunger that usually hum along all day – once their eating window had closed.
The results suggest another way healthcare providers can set people up for success on time-restricted eating: coach them to aim for big-picture consistency and not perfection.
Bjerre learned that how people respond to occasional time-restricted eating slip-ups is crucial. “Some participants felt like a failure or felt shame” if they ate dinner an hour too late one day, she says, whereas the people who adapted well to time-restricted eating gave themselves more grace.
Healthcare providers should emphasise that time-restricted eating is a marathon and not a sprint. “Missing one day or one window is okay – the next day is a new day,” Quist says.
