DR MICHAEL MOSLEY: How to diet without even noticing? Don’t eat after 7.30pm

When our kids were young my wife Clare and I were often so busy in the early evening — feeding them, putting them to bed and reading them stories — that we’d end up collapsed in front of the TV, before then cooking the evening meal. This meant we’d often find ourselves eating well after 9pm.

But more recently we’ve made an effort to start eating our dinner by 7.30pm, as well as avoiding too many late-night snacks.

Doing so is almost certainly good for the waistline, as a recent study from the University of Nottingham and Tehran University of Medical Sciences in Iran confirmed.

What is clear from many studies is that our bodies don’t like having to deal with lots of food late at night. A midnight snack will have a worse impact on you than the same food eaten earlier in the day [File photo]

The researchers had asked 82 healthy but overweight women to go on a weight-loss programme — the women didn’t normally finish their evening meals until well after 10pm, but now half were asked to finish their eating by 7.30pm at the latest.

After 12 weeks both groups had lost weight, but those who changed to eating earlier in the evening had lost an average of 15lb, compared with less than 11lb for the late eaters. In other words, just by changing the time they ate the early eaters had shed an extra 4lb. They also lost an extra inch around the waist and experienced greater improvements in their cholesterol and blood fats.

This wasn’t because the later-eating group consumed more — the two groups essentially had the same calorie intake. Instead, the researchers think that, among other things, late-night eating might affect the genes that control your body clock, leading to a greater risk of obesity (and type 2 diabetes).

I wasn’t entirely surprised by this because a few years ago, as part of a science documentary, I did an experiment where I ate a classic British fry-up, with lots of bacon, eggs and sausage, at 10am and then again at 10pm.

Straight after my morning meal I had a blood sample taken, and then again every half-hour for the next few hours. 

After that, I had nothing but water until 10pm, when I had exactly the same meal. Again, my blood was taken regularly over the next few hours.

More recently we’ve made an effort to start eating our dinner by 7.30pm, as well as avoiding too many late-night snacks. Doing so is almost certainly good for the waistline, as a recent study from the University of Nottingham and Tehran University of Medical Sciences in Iran confirmed [File photo]

When the results of the blood tests came back, they were pretty shocking. After eating a full English fry-up in the morning my blood sugar and fat levels quickly rose, but soon returned to normal as my body used them as fuel, or stored them around my gut for later.

What happened in the evening, however, was very different. Despite eating exactly the same meal, my blood sugar levels went up and stayed high for several hours. The fat levels in my blood were even worse, still rising at 2am, four hours after I’d finished eating. And the next morning I woke up feeling knackered — and starving.

Further proof that late-night eating really does alter your ability to handle food comes from a recent study by Johns Hopkins University School of Medicine in the U.S., which found that when healthy volunteers had their dinner within an hour of going to bed, they burnt 10 per cent less fat overnight than when they stopped eating three hours before shut-eye.

What is clear from many studies is that our bodies don’t like having to deal with lots of food late at night. A midnight snack will have a worse impact on you than the same food eaten earlier in the day.

Not only is this because late-night eating alters your body clock, but it also seems to alter your microbiome, the 100 trillion microbes that live in your gut. Eating late encourages the growth of ‘bad’ microbes that raise inflammation (long term, a risk for health as it damages healthy tissue).

Finally, we know that your gut needs downtime, to get on with essential repairs. It is a bit like a motorway, which takes a terrific pounding from all the traffic that goes along it.

Just as you can’t patch up a motorway when there are cars and lorries travelling along it, your body can’t get on with its repairs while you’re constantly eating.

The changes in the body clock caused by late-night eating may also help explain why shift workers are at greater risk of certain cancers. We know, for example, that women who work nights have an increased risk of breast cancer. Working (and probably eating) at night affects the body clock, and in turn, disrupts the release of hormones. Many cases of breast cancer are linked to abnormal hormone levels.

No one has yet carried out a trial to test the impact of late-night eating on breast cancer, but the Women’s Healthy Eating and Living study shows timing could be significant.

This trial involved around 2,400 American women with breast cancer who were randomly allocated to either a low-fat diet or given a pamphlet on the benefits of ‘five-a-day’. They were then monitored for over seven years to see if going low fat reduced the risk of their breast cancer recurring.

The answer was a resounding ‘no’. Despite reducing their fat intake by 19 per cent, the low-fat dieters were no better off than the control group.

But the interesting thing is that the women were asked to keep detailed records of not only what they ate, but when they ate. And those who typically ate after 8pm were significantly fatter than those who ate earlier; they were also at greater risk of breast cancer recurrence.

Although I now try to eat my evening meals by 7.30pm (an arbitrary time based on what is convenient), this would still be considered late in some countries.

In Norway they typically eat their evening meals by 5pm. Since the Norwegians are regularly rated as among the healthiest and happiest people in the world, perhaps we should all follow their example.

I’m a huge fan of taking the stairs: not only do you burn three times more calories than when using the lift or escalator, there’s also strong evidence that everyday activity, such as regular stair climbing, is good for your mood, too. 

And now researchers at the Karlsruhe Institute of Technology in Germany have found that this kind of nonexercise activity may be particularly beneficial for the mental wellbeing of people with mood disorders (such as depression).

The news that the Oxford-AstraZeneca vaccine is safe and appears to be up to 90 per cent effective is very welcome. But as with so many breakthroughs, this one owed a lot to chance.

Like the other Covid jabs, the Oxford vaccine is given in two shots. You might imagine it would be best to give the biggest safest dose each time. And that’s what happened to 8,895 volunteers in a recent trial.

But a mistake meant that another 2,741 had a much lower initial dose, followed by a full dose. This still produced a good response, so the researchers decided to use this approach. 

It’s a good thing they did because it turned out it was the volunteers given a low dose first who got the 90 per cent protection (compared with 62 per cent for those given the maximum safe dose twice).

This was not entirely unexpected: research with a similar type of vaccine in mice found that a low first dose followed by a high second dose often led to better protection.

One theory is that a low dose is better at quickly triggering the development of ‘memory’ immune cells. Whatever the reason, it’s a mistake that could benefit millions of us!

A good excuse to stay in bed!

For those of us who are a bit lazy about changing our bed sheets, there was good news this week, with a report suggesting that the microscopic creatures that share our beds may actually boost our health.

When researchers from the University of Copenhagen in Denmark analysed bed dust (made up of old human skin) from the beds of 577 infants, they found nearly a thousand different types of bacteria and fungi. And the number of species was highest in boys living in rural areas who had a pet.

We’ve known for some time that exposure to a wide range of microbes, particularly early in life, is linked to a reduced risk of conditions such as asthma, obesity and type 2 diabetes. The thinking is that regular exposure to bugs helps train our immune systems in how to behave (and not overreact, as happens with allergies).

As the lead researcher, Søren Sørensen, put it: ‘The simple message is that constantly changing bedsheets may not be necessary.’ (Although in classic researcher terms, he added a caveat: ‘[But] we need to investigate this a bit more closely before being able to say so for sure.’)