When I was a student, there was a simple mantra in nutrition: “If the number of calories eaten exceeds the number of calories expended, you will put on weight”. That was the ultimate equation to life, the universe and obesity.A calorie is a calorie; basic physics with which no-one can argue. But, as everyone started to ask – if the equation is so simple, why has overweight and obesity continued to rise in the UK to the point where nearly 2/3 of all adults fall into either category, while overall energy intakes have barely changed? As a distinguished Professor of mine once said: the equation is simple – but what happens within in the body is far more complicated.
New and exciting research in this area has recently appeared on BBC2’s ‘Trust me, I’m a Doctor’ (shown on January 13th 8.00pm). Dr Michael Mosley fronts the show, and often presents pieces about nutrition. His excellent 2012 Horizon documentary, ‘Eat, Fast and Live Longer’, led to the popular ‘5/2 diet’ which you may have come across. For this programme, the team examined new evidence that calories consumed at different times of the day, and over different parts of the day, have different effects on health. The two main conclusions were: if we eat our daily calories closer together, and leave more time when we are not eating at all, we can actually improve our health, and; a large meal consumed late in the evening can have a more damaging effect on the body than the exact same meal consumed earlier in the day.
Evidence of these effects have mainly been shown in animal research, whereas evidence in humans has been scant. So, for the programme, a small group of healthy volunteers were split into two groups for a 10 week experiment. The control group ate their typical diet as usual. The test group also ate their typical diet, but they brought their meals closer together by eating breakfast 90 minutes later than usual, and dinner 90 minutes earlier than usual, with no evening snacking. Thus, although the calories consumed in the test group were exactly the same as normal, the volunteers had effectively increased the time they were ‘fasting’ (between dinner one day and breakfast the next ) by 3 hours every day.
The results? After 10 weeks, those in the test group had a lower percentage body fat, lower blood glucose levels, and lower blood cholesterol levels. In effect, they were healthier simply by changing when they ate their meals.
Amazing. How is this happening? Dr Jon Johnston, a researcher from Surry University who led the study, said there were two current theories. First, the test group were eating meals at times when the body was ‘expecting’ them, meaning that they could metabolise them better. This effect was demonstrated earlier in the programme when Dr Mosley ate two identical meals (a fry-up) at 10 am and 10 pm in the same day, and it was shown that his blood glucose and fat levels stayed higher for longer after the evening meal than after the morning one. The idea here is that the body naturally increases blood glucose and fat levels in the evening to sustain the body during sleep, and that a big meal late at night will detrimentally add to this rise. It’s interesting that the programme also noted average dinner times in the UK have switched from 5.30pm to nearly 8pm over the past 10 years.
The second theory is that longer periods of fasting seem to be better for us anyway, as they allow the body to switch from ‘growth’ mode (during eating) to ‘repair’ mode (during fasting), which is also associated with positive changes in health. Whatever the mechanisms, this area of nutrition research research is really hot stuff at the moment – it flies in the face of conventional wisdom, and suggests that metabolically, a calorie’s no longer just a calorie.
As a practitioner who integrates both modem scientific research and traditional medicine in my approach, and I always get very excited when ideas and theories from such apparently diverse sources start to agree. I’ve been following research on the health effects of fasting and meal timings for a number of years now, and it is one of the main approaches I take with my clients. What’s also interesting is that many traditional approaches to diet also agree. In Ayurvedic medicine for example, different meal patterns are prescribed for different of people, and it is often suggested to eat only during daylight hours. And of course, you’ve all heard the saying “Eat breakfast like a king, lunch like a prince, and supper like a pauper”, attributed to controversial US nutritionist Adelle Davies back in the 1960’s?
In my next post, I shall investigate in more detail the health effects of fasting, and how modern research has started to uncover amazing health benefits of this ancient practice.
Dr Rafe Bundy, January 2016
To read more about Rafe and the service he provides, please follow this link to his webpage