Eating your dinner just a tad earlier, or pushing breakfast to mid-morning, may be the newest science-backed way to lose weight.
Research published in the journal Cell Metabolism on Thursday suggests that eating only during a 10-hour window every day (for example, 8 am to 6 pm, or 10 am to 8 pm) is ideal for overall health. This is slightly less time than the typical 14 to 15 hour spread that people tend to spend eating throughout the day.
“We thought a 10-hour eating window was very doable for most people,” lead study author and UC San Diego cardiologist Pam Taub told Insider. “And the results are pretty amazing, in terms of reduction in weight, reduction in bad cholesterol, reduction in blood pressure.”
For the study, researchers focused on a small group of 19 overweight adults with metabolic syndrome issues like high blood pressure, excess belly fat, and high cholesterol, who were on some medications for those conditions.
The researchers tracked patients for three months on their time-restricted 10-hour a day eating plan. They found the self-prescribed eating routines (which people could adjust to fit their schedules) not only helped patients lose more weight than they would by restricting calories or trying to exercise more, but the participants also achieved powerful reductions in bad cholesterol levels and cut their belly flab down measurably, while also sleeping more soundly and feeling energized.
Study participants lost over half a pound each week, on average
Participants in the study lost an average of a little more than half a pound a week (0.6 lbs) during the study, which is considered safe for weight loss.
“We didn’t specifically ask anyone to restrict their calories,” Taub said. “We just told them to restrict their eating window. And one of the nice things is people – inadvertently without even meaning to – do reduce their calories by a little bit.”
Nearly two-thirds of the patients continued adhering to their fasting routine for at least a year after the study ended because it made them feel better. Some were able to quit or reduce their cholesterol or blood pressure medications. Taub told her patients that they should aim to eat nutritious, healthful meals during the study, but stressed “not to starve” and “not to be very skimpy on the calories.”
“This is not a caloric restriction diet,” she said. “We do tell them during those 10 hours to eat, and be content. And I think that’s what’s also self-sustaining is people don’t feel hungry. People don’t feel deprived.”
Taub says that she’s adopted a version of the same fasting plan, and now typically restricts her eating to between the hours of 8 am and 6 pm. Many of her friends and family are trying out their own versions of the idea.
“I’m basically having dinner just a little bit earlier, and having dinner be very, very light – the lightest meal of the day,” Taub said. “Our suggestion for when to eat is really during the daylight hours. So we’re also aligning the circadian biology with the food intake, because all of our organs have clocks, internal clocks, and they like to be active at certain times.”
Intermittent fasting is popular, but not all strategies for it are safe
People around the world have known for centuries that fasting can do a body good. Periodic fasting can help ward off diseases like diabetes, high cholesterol, and obesity; it can boost the production of a protein that strengthens connections in the brain; and it can serve as an antidepressant. Scientists even think fasting may lengthen our lifespans by keeping cells healthy and youthful.
But the question of how often and when to fast is still the subject of much debate. Recently, a brand of fasting called “intermittent fasting” or “I.F.” has been touted as a straightforward way to lose weight, but there are different definitions for what the term means.
Many people adhere to a popular 16:8 plan, which involves eating for eight hours each day and fasting for the remaining 16. While this particular plan is generally considered healthy, some people report issues with nausea, bowel movements, and vomiting when their feeding time is limited to 8 hours. Others go to more dangerous extremes with their fasting escapades.
“They’re reading things on the internet that tell them to skip breakfast, or you fast for two days, or you fast for one week, and so there’s just a lot of confusion out there,” Taub said. “We wanted to come up with something that was really doable that everybody could do and not feel deprived and still maintain all of their routines.”
Patients in the study were allowed to have a cheat day
The researchers behind this latest study even allowed their patients a “cheat” day once a week, letting them eat for a slightly longer period of time. They still saw measurable health improvements.
Patients lost about 3% of their body weight, a figure that would normally be associated with a roughly 5% reduction in “bad” LDL cholesterol. Instead, the patients reduced their bad cholesterol by a whopping 11%.
“The benefit of time-restricted eating goes beyond just a decrease in calories,” the cardiologist said. “I tell my patients, if you can do at least five days a week, that’s a good way to start.”
Fasting works because it helps give our cells a break
Though this study was done in overweight patients, other recent work has suggested that the same technique can improve the health of other adults on a cellular level.
“I’m not saying food is our enemy, absolutely not, we need to eat otherwise we die,” cancer researcher Dr. Miriam Merad told Insider when her recent study on intermittent fasting in a dozen healthy adults was released. “But it is true that we probably eat too much … we eat too often.”
The reason why fasting is good for us, Merad suspects, may have to do with a type of immune cell called a monocyte, which our bodies typically release to fight off infections and wounds.
Monocytes are inflammatory, and the white blood cells can cluster to heal the body when we’re injured. But any time we eat food, monocytes are also standing guard in case we ingest any threatening microorganisms. This is especially true when we consume sugar. Monocytes also accumulate in fat tissue, contributing to chronic disease.
Taub has another cellular-level theory about the benefits of fasting that she’s testing out in a multi-year trial funded by the National Institutes of Health. Her hypothesis is that fasting helps support the health of our cells’ mitochondria, which are integral to the body’s metabolism. Regular fasting, she suspects, may help our mitochondria operate more efficiently.
“When you give your body a good period of fasting, it allows a lot of the cellular repair and regeneration to occur,” she said. “Because when you consume calories, it’s making the body work.”
Author: Hilary Brueck