Learn to time your meals right to fight of f the f lab

At any given time, about half the world’s population is trying to lose weight. For millions of us, dieting is an over-whelming preoccupation.

But guess what? this, too, is influ-enced by our circadian rhythms. and if we ignore it, we will be undermining any efforts we’re making to maintain a good diet and take regular exercise.

your body clock influences every aspect of your metabolism, from hunger and digestion to when hormones and enzymes related to your metabolism are produced.

Under normal circumstances we eat during the day — that’s why our body is primed so that saliva production rises over the day and falls at night. and (as we now know) our stomach naturally empties faster in the morning than in the evening.

But if anything throws this cycle off — such as eating very late at night, when the body isn’t ‘ready’ for food — it won’t take long for chaos to ensue and our metabolism to become far less efficient.

this has been shown in mice studies, where the rodents were made to feed at a time they should normally be asleep. Remarkably, the clocks in the animal’s livers, muscles, gut and other organs ‘moved’ their circadian rhythms to coincide with the new feeding time.

However, the master clock in the brain remained locked on to the old light/dark cycle. as a result, the master and peripheral clocks were no longer aligned with each other — and the normal metabolic pathways that underpin the different demands of sleep and activity were severely disrupted.

Long term, this led to obesity and metabolic problems such as

type 2 diabetes.

SO WHAT does this mean for us? Studies have shown a clear link between night-shift work, metabolic syndrome (a group of conditions that includes high blood pressure and obesity) and high blood glucose, or sugar, leading to type 2 diabetes. this is because the workers are forced to work and eat when their bodies expect them to be asleep.

the same could happen to anyone who regularly eats when they should really be asleep. the disruption means we are far less likely to mop up blood glucose because we can’t release sufficient insulin (which acts to lower blood glucose) at this time of night which, in turn, greatly increases our chances of weight gain and type 2 diabetes.

the disruption to our body clocks also sends our hunger hormones haywire. these are leptin, the ‘satiety signal’, and ghrelin, the ‘hunger hormone’ which stimulates appetite.

Recent studies have shown that leptin release peaks at about 2am (when you’re sleeping) and the low point is around noon (when you’re active). normally, high levels of leptin at night suppress appetite so that hunger doesn’t disrupt your sleep.

Meanwhile, ghrelin is secreted by the stomach during the daytime and increases in anticipation of meal times.

the release of these hormones programmes our bodies to expect a large meal in the morning and at lunchtime, with a smaller meal in the evening and nothing at night.

But people whose sleep is interrupted have consistently lower levels of leptin and raised ghrelin, increasing their hunger so they eat more food. a classic study examined the impact on healthy young men of having only four hours of sleep on two consecutive nights.

In these young men, blood levels of leptin decreased by 18 per cent, while ghrelin (to remind you, that’s the hunger hormone) increased by 24 per cent. the same increase was recorded in their levels of hunger and appetite. these findings strongly suggest that we are effectively programmed to consume more calories when we are deprived of sleep.

TRY TO BREAKFAST LIKE A KING!

THE good news is that eating at the right time can truly maximise our chances of maintaining a healthy weight.

the philosopher and physician Maimonides (1138–1204) is remembered for many things, but by me most pertinently for the saying, ‘eat like a king in the morning, a prince at noon, and a peasant at dinner’.

this philosophy makes him the founding father of ‘chrononutri-tion’, the science that’s identified that when we eat is just as critical for health as what we eat.

while in Maimonides’ time the largest meal of the day typically was breakfast, over time the main meal of the day has — with the advent of artificial light, industrialisation and changes in working practices — moved later and later.

today, long commutes, irregular hours, the pressures of school work and the availability of micro-wave food have all pushed the major meal of the day to an irreg-ular mid to late-evening slot.

If you were designing a schedule to be particularly bad for our circadian-regulated metabolism, this would be it.

FoR as I’ve explained, eating in the evening when your body isn’t expecting it greatly increases your risk of developing glucose intolerance, type 2 diabetes, weight gain and obesity.

a detailed study in 2013 compared people on the same 20-week reduced-calorie diet, consuming most of their calories either early or late in the day. those who ate late in the day lost less weight, more slowly.

Importantly, the same meal in the evening results in higher levels of blood sugar than if eaten in the morning — the result of the normal body clock cycle preparing itself for a sleep-time metabolism with no food intake.

the simple answer? Go back to the old-fashioned principle of a big breakfast, a hearty lunch and a light, early, evening meal. and don’t raid the fridge at midnight! n AdApted from Life time:

the New Science Of the Body Clock And How It Can Revolutionise Your Sleep And Health by Russell Foster, published by penguin Life on May 19 at £16.99. © Russell Foster 2022. to order a copy for £15.29 (offer valid until May 21, 2022; UK p&p free on orders over £20), visit mailshop.co.uk/ books or call 020 3176 2937.