People are often encouraged to eat like a king at breakfast and reduce meal size as the day progresses. Is this based on evidence? Does it really matter when we eat our calories?
A study with 193 obese participants compared two different dietary patterns that had similar calorie intakes. Their main aim was to see if it made any difference to weight loss, which they measured, but also hormones responsible for hunger. One group ate a small amount of their daily calorie intake at breakfast while the other ate a larger amount at breakfast. Every four weeks the researchers conducted tests to see how they were getting on across a 32-week period. At week 16, both groups exhibited similar weight loss. However, from week 16 to week 32, the group with the small breakfast started to regain weight. During this period, the group who ate a larger breakfast continued to lose weight.
The reason for this trend was put down to feeling full. The satiated feeling was shown to be significantly better in the bigger breakfast group, with hunger and craving scores also significantly reduced. This was bound to make sticking to the weight loss programme easier.
Breakfast is best
A follow-on to this study looked at a similar dietary pattern but this time looked at whether it had any impact upon metabolism. Both groups of overweight people ate a 1,400-calorie-a-day diet, with one group eating 700kcal at breakfast, 500kcal at lunch and 200kcal at dinner, while the other group did the opposite, eating 200kcal at breakfast, 500kcal at lunch and 700kcal dinner for 12 weeks. The bigger breakfast group showed greater weight loss and greater reductions in waist circumference.
Both groups had improvements in fasting glucose, insulin and ghrelin (a hunger hormone). However, the bigger breakfast group also showed significant improvements in fasting glucose, insulin and insulin resistance. Intestinally triglyceride levels, a marker in heart health, decreased by 33pc in the big breakfast group, but increased by 15pc in the big dinner group.
Again we see that having a bigger breakfast and decreasing your meal size as the day progresses lead to greater weight loss, more controlled hunger levels, and improvements in metabolic health.
As this way of eating becomes more accepted as healthier, scientists are looking at the benefits of reducing your eating window. For example, they’re looking at whether it would be best if we were to sleep for eight hours a day, fast for an eight-hour period during the day, and only eat during the remaining eight hours.
The eight-hour rule
The idea behind the research was based on the body having an internal clock. As many aspects of metabolism function optimally in the morning, they hypothesised that by eating in line with the body’s circadian clock you may positively influence health. Plus, it leads to less time for snacking, especially in the evening time.
Scientists wanted to know whether eating a very early dinner provided benefits for losing weight.
A 2014 study followed 11 men and women with excess weight over four days of eating between 8am and 2pm, and four days of eating between 8am and 8pm. Eating in a 12-hour window is something many Irish people do.
The researchers looked at calories burned, fat burned and markers of appetite. All participants ate the same number of calories in both feeding time frames. The smaller eating window didn’t affect how many calories participants burned. However, it did reduce hunger levels and increased fat burning for several hours at night. It was also seen to improve metabolic flexibility, which is a phrase used to describe the body’s ability to switch between burning carbohydrate stores and fat stores.
Larger and more comprehensive research is required in this area.
Eat early or late?
Another study, published in 2016, looked at something quite similar. On this occasion 34 men, trained in resistance-style exercise, were randomly selected to follow a time-restricted feeding pattern or a normal diet for eight weeks. As most studies focus on restricted eating patterns in overweight, people this study was interesting as it focused on a more healthy bunch of people.
The subjects following the time-restricted pattern ate 100pc of their calorie requirements in an 8-hour period each day. Their calorie intake was split into three meals. However, unlike the other study, which focused on the first half of the day, the meals in this study were consumed at 1pm, 4pm and 8pm. The other group of participants ate in the standard breakfast, lunch and dinner routine at 8 am, 1pm and 8pm. Both groups ate the same amount of calories and their macronutrients (carbohydrates, proteins and fats) were distributed the same way. They all followed a standardised resistance training program.
After eight weeks, the time-restricted feeding group showed a decrease in fat mass that was significantly different to the people following the normal diet. Lean tissue and strength were maintained in both groups.
Although there was no difference between the two groups with regards to resting metabolism, there was a significant decrease in ‘respiratory ratio’ observed in the TRF group. They also exhibited lower testosterone levels.
In some women, such as those with polycystic ovary syndrome (PCOS), a reduction in testosterone levels may be helpful.
More studies are required, of longer length, to see if such time-restricted eating could also work to improve fertility for PCOS sufferers, and reduce other symptoms associated with the syndrome, including excess body hair, hair loss and acne.
Although many people wouldn’t be willing to try this sort of meal plan, as obesity levels are climbing it is important to find as many solutions as possible.
Will this way of eating suit everybody? Probably not. But one diet does not fit all.
Top tips to get going
1 Get the ball rolling by cutting back on how much you eat this evening. Tomorrow morning you’ll wake up hungrier than usual.
2 Try and do a little bit of exercise in the morning to stimulate your appetite at breakfast. This doesn’t have to be the gym, why not try and go for a short walk outside?
3 From now on, eat from a large plate or bowl in the morning and from a small plate or bowl for your evening meal.
4 Choose lots of healthy protein for breakfast to help increase satiety. For example, milk and yoghurt or a naturally lower fat cheese like cottage cheese or quark. Or why not go savoury with turkey rashers and beans or eggs and smoked salmon?
5 As with all healthy meals, add a splash of colour to your plate by adding some fruit and veg.