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 i n 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.

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 latereating 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.

When the results of the blood tests came back, they were pretty shocking. After eating a big 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 f ood comes f rom 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 latenight eating alters your body clock, but it also seems to alter your microbiome, the 100 trillion microbes that live in your gut. eating l ate encourages t he growth of ‘ bad’ microbes that raise inflammation (long term, a risk f or 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 f atter 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.