It has long been said that the secret of good health is to breakfast like a king, lunch like a prince and dine like a pauper.
Now, scientists have gone one further – concluding that the best way to get into shape is to eschew all meals after 3pm.
Intermittent fasting has grown in popularity in recent years. Advocates suggest that skipping meals emulates the habits of our hunter-gather ancestors, who did not have access to food around the clock.
Now researchers who reviewed 250 studies on diets and lifestyles have concluded that fasting for around 15 hours a day is optimal for health and weight loss.
Eat early for weight loss
The research found that dieters who ate early were most likely to achieve significant weight loss.
One study of women on calorie-controlled diets for 12 weeks found that those who ate most of their meals early in the day lost 11lbs more than those eating the same calories spread over the day.
In the latest review of the evidence, scientists found that feasting early was associated with a host of other health benefits – reducing blood pressure, inflammation and risk factors for diabetes.
When dieters were allocated the same calories, eating earlier in the day was linked with greater weight loss. And in other studies, where slimmers were given more free rein over their diet, eating earlier in the day appeared to regulate appetite – reducing overall calorie intake.
The findings, presented at the European Congress on Obesity in the Netherlands, suggested that the best results came from eating all meals before 2pm or 3pm.
Scientists said sticking to this pattern worked best with the body’s circadian rhythms, harnessing its natural body clock, making it better at processing blood sugar and boosting healthy gut bacteria.
‘Time-restricted eating’ becomes popular
Dr Courtney Peterson, associate professor and co-director of the Sleep and Circadian Research Core at the University of Alabama in Birmingham, USA, said: “Time-restricted eating is becoming wildly popular. People typically eat within something like an eight to 10-hour window and so they’re effectively fasting for 14 to 16 hours a day.”
The researcher said consistent meal times helped to boost health, avoiding a kind of “metabolic jetlag” that could be fueled by changing habits.
“We think benefits come when it is the same eating time window each day,” Dr Peterson said. “The reason for this is you have an internal biological clock, called the circadian system.
“Your highest alertness, testosterone production and, in most people, best blood sugar control is in the morning. So your metabolism is kind of optimized.
“One of the things that’s really important about having these optimal circadian rhythms is doing the same thing at a consistent time of day.”
One study by Dr Peterson’s team in the US found people were less hungry when eating on an 8am to 2pm regimen than if the six-hour eating window occurred later in the day. They concluded that eating early regulated the appetite.
A second study by the same team found such timings increased gene expression and hormone levels, which could explain its anti-aging effects seen in animal studies.
Separate research on pre-diabetic men who ate all their meals in a window of just six hours, ending at 3pm, found significant benefits in insulin sensitivity, within just five weeks, cutting the risk of diabetes.
A host of other health improvements were seen, researchers said, including a 10-point drop in blood pressure and improvement in a kind of molecular damage in the body called oxidative stress.
The body of research suggested that shifting dinner forward by a couple of hours was not sufficient to make a difference.
Dr Peterson said: “Some of the recent studies where they’ve tested having people eat in a 12-hour window and fast for 12 hours a day haven’t found any additional benefits.”
‘Painless’ way to lose weight
Tam Fry, from the National Obesity Forum, said: “The mantra ‘breakfast like a king, lunch like a prince and dine like a pauper’ couldn’t be better to describe this research.” He said such changes offered a “painless” way to lose weight.
He added: “A right royal breakfast is hugely important to get your day off to a good start and lunch should still be something substantial. And that’s more or less it. Any further eating should be minimal and eaten early in the evening.”
Chinese research, which tracked 90 volunteers, found that restricting food to the early part of the day, rather than the afternoon, was most effective.
The paper, published in Nature Communications, found: “Western-style diets, which include fat-rich food and snacks that are consumed around the clock, play a causative role in the development of some chronic diseases. In contrast, our human ancestors did not have continuous access to a food supply.”