I have spoken a bit about the hidden calories in places, but calories are definitely not everything that matters. Within our bodies are biological processes that are influenced by the day and night cycles. So that means that different parts of our body are more or less active at different times of day and night. You would have noticed this – that sometimes we naturally feel awake during the day and tired at night. These systems are called circadian rhythms. Our circadian rhythm is basically a 24-hour internal clock that is running in the background of your brain and other parts of your body and cycles between sleepiness and alertness at regular intervals. It’s also known as your sleep/wake cycle.
The circadian system is composed of a master clock and a whole series of clocks throughout the body that work together to help you function and stay healthy. The central master clock is in the suprachiasmatic nucleus, located in the hypothalamus of the brain. However, there is also more and more evidence suggesting that many other organs and cells in the body have their own clocks which influences their function. Meaning that they are operating differently at different times of day and night.
In particular, the liver and gastrointestinal tract have their own internal clocks. What this is starting to mean is that there may be better times to eat. There may be times during the day where our bodies naturally are better able to process foods and use that food well and other times when eating could cause damaging effects. So, the same food eaten at a different time could have significantly different outcomes – good or bad, depending on the time you eat it.
Common sense would say that we should sleep at night and therefore should not eat at night when the body is not biologically ready for it. And we are seeing evidence for now that.
In 2013 2 studies demonstrated this well. In one study 93 overweight and obese women with metabolic syndrome, researchers assigned some to eat more of their calories during breakfast with fewer at dinner, and others more at dinner and less at breakfast. After 12 weeks, despite similar total calories, women consuming a greater proportion of calories earlier in the day lost 2.5 times more weight compared to women who had most of their calories at dinner. They also had greater drops in waist size, fasting blood sugar, insulin resistance which can lead to diabetes, and blood cholesterol than the other women. In another study of 420 people found that people who chose to eat earlier lost about 25% more weight than people who ate later.
So the short version of this early evidence is that if two people eat exactly the same food but one eats most of it in the earlier parts of the day and other later – the one who eats it earlier in the day is going to lose more weight, reduce their blood sugar levels and cholesterol far more effectively than the person who eats the exact same amount of food but at the end of the day.
Whilst it is early days to be making concrete conclusions about this, I think it is logical and reasonable to focus on eating most of your food at breakfast and lunch and only light meals after this. This can sync in with the natural cycles of your body when your body is most able and prepared to process this food. This is a low-risk change you can make that may have huge benefits to your whole body.