You can lose up to a stone in three months by eating all your meals between 7am and 3pm, a study suggests.
Obese adults who ate within an eight-hour window lost 14lbs (6.3kg) in 14 weeks, on average, compared to 9lbs (4kg) in a control group who ate when they wanted.
Both cohorts were given expert advice on how to follow a diet and what foods to eat, and put on the same exercise regime.
It suggests limiting the amount of time we spend eating limits the amount of calories we consume by default, according to the researchers.
Fasted people in the study were found to consume the equivalent of a Mars bar less food per day compared to the non-fasted group.
Intermittent fasting has been a trendy diet plan favoured by Hollywood stars like Jennifer Aniston, Benedict Cumberbatch and Nicole Kidman for years.
As well as weight loss, the practice has been linked to longevity and a reduced risk of age-related diseases.
The study found restricting eating to between 7am and 3pm each day helped obese dieters shed an extra 5lbs in 14 weeks compared to just dieting and exercising alone
Intermittent fasting has been a popular form of dieting among Hollywood A-listers like Jennifer Aniston who in 2019 said she doesn’t eat breakfast and only consumes liquids in the mornings, saving her eating until the final half of the day (pictured here in May this year)
Nicole Kidman, pictured here in Paris last month alongside husband Keith Urban has also reportedly used intermittent fasting
And Benedict Cumberbatch, pictured here at a screening of Doctor Strange In The Multiverse Of Madness in New York back in May, reportedly used the the 5:2 fasting method to shed pounds for the role of Sherlock in the BBC drama of the same name
British experts called the results encouraging but said more research needed to be done on if the weight loss and health benefits observed could be sustained in the long run.
Obesity is a massive issue for both the US and the UK, with both countries facing increasing healthcare bills for the cancers, heart disease and other health problems that come with being too fat.
In the study, scientists from the University of Alabama took 90 obese adult Americans and put them on the same diet and exercise regime.
What is intermittent fasting?
Intermittent fasting involves switching between days of fasting and days of eating normally.
Intermittent fasting diets fall generally into two categories – time-restricted feeding, which narrows eating times to 6-8 hours per day, also known as the 16:8 diet, and 5:2 intermittent fasting.
The 16:8 diet is a form of intermittent fasting, also known as Time Restricted Eating.
Followers of the eating plan fast for 16 hours a day, and eat whatever they want in the remaining eight hours – typically between 10am and 6pm.
This may be more tolerable than the well-known 5:2 diet – where followers restrict their calories to 500–to-600 a day for two days a week and then eat as normal for the remaining five days. In addition to weight loss, 16:8 intermittent fasting is believed to improve blood sugar control, boost brain function and help us live longer.
Many prefer to eat between noon and 8pm as this means they only need to fast overnight and skip breakfast, but can still eat lunch and dinner, along with a few snacks. When you do eat, it is best to opt for healthy options like fruits, vegetables and whole grains.
And drink water and unsweetened beverages. Drawbacks of the fasting plan may be that people overindulge in the hours they can eat, leading to weight gain.
It can also result in digestive problems over the long-term, as well as hunger, fatigue and weakness.
Participants in the study were mostly women (80 per cent), had an average age of 43 and had a body-mass-index (BMI) of 39.6.
For context a BMI of 40 or above is considered severely obese.
Both study groups were given advice from a dietician on how to follow the special weight loss diet, which they had to stick to for six days a week.
They were also told to exercise between 75 to 150 minutes per week.
Those on the fasting regime were also found to have healthier blood pressure and reported being happier than before starting the test.
Publishing their findings in the journal JAMA Internal Medicine the authors said: ‘The effects of early-in-the-day time-restricted-eating were equivalent to reducing calorie intake by an additional 214 calories per day’.
Nearly half (41 per cent) of the fasting group planned to continue practicing the same eating routine now the study had concluded.
The authors said the study was limited in that it looked mostly at females and relied on self-reporting to tell if people followed the diet and exercise plans.
Professor Naveed Sattar, an expert in metabolic medicine at the University of Glasgow who was not involved in the study, said: ‘This is interesting and encouraging but it is a very small trial with short follow-up so longer term trials over a year or longer are needed to see if people can keep up this behaviour and maintain all reported short term benefits,’ he said.
Professor Peter Hajek, a health behaviours expert from Queen Mary University of London, said the study added to a body of work showing fasting can help achieve short term benefits.
‘This small trial provides additional evidence that time-restricted eating can contribute to weight loss over short term (14 weeks) if combined with caloric restriction,’ he said.
However, he added questions remained over the sustainability of the diet and called for larger studies.
‘Time-restricted-eating is an exceptionally simple and practicable intervention that may have a better potential for being manageable over long-term than most alternative methods,’ he said.
‘A proper large trial of time-restricted-eating on its own with long-term follow-up is now needed.’
The findings are contrary to a Chinese study on intermittent fasting published in April that found the trendy dieting plan was no more effective than restricting calorie intake.
Trendy fasting diets have been popular since the 2010s, and adopted by various celebrities such as Jennifer Aniston, Reese Witherspoon and former Twitter CEO Jack Dorsey, as well as Benedict Cumberbatch.
In October 2019, Jennifer Aniston said she doesn’t eat breakfast and only consumes liquids in the mornings, saving her eating until the final half of the day.
Actor Benedict Cumberbatch is also reported to have used the 5:2 intermittent fasting method to shed the pounds as the lead character in the BBC drama Sherlock.
The NHS warns against following ‘fad diets’ and exercise regimes, stating they are unlikely to work for long because these kinds of lifestyle changes cannot be maintained.
Instead, the NHS said people should make realistic changes to their diet and physical activity levels that result in a steady rate of weight loss until their achieve a healthy BMI.
Having too much fat is considered one of Britain’s biggest and ever-expanding health issues, with the latest data showing 64 per cent of adults are overweight.
In the US an estimated 73.6 per cent of adults are considered either overweight or obese.
Being overweight or obese is known to increase the risk of at least 13 different types of cancer and causes other dangerous conditions such as high blood pressure and type 2 diabetes.
Treating obesity and overweight related heath problems has been estimated to cost the NHS about £6.1billion each year.
WHAT SHOULD A BALANCED DIET LOOK LIKE?
Meals should be based on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain, according to the NHS
• Eat at least 5 portions of a variety of fruit and vegetables every day. All fresh, frozen, dried and canned fruit and vegetables count
• Base meals on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain
• 30 grams of fibre a day: This is the same as eating all of the following: 5 portions of fruit and vegetables, 2 whole-wheat cereal biscuits, 2 thick slices of wholemeal bread and large baked potato with the skin on
• Have some dairy or dairy alternatives (such as soya drinks) choosing lower fat and lower sugar options
• Eat some beans, pulses, fish, eggs, meat and other proteins (including 2 portions of fish every week, one of which should be oily)
• Choose unsaturated oils and spreads and consuming in small amounts
• Drink 6-8 cups/glasses of water a day
• Adults should have less than 6g of salt and 20g of saturated fat for women or 30g for men a day
Source: NHS Eatwell Guide