Later meal times ‘make us more likely to put on weight’

Eating meals late in the day makes you more likely to gain weight, and susceptible to conditions including diabetes and heart disease.

That is according to the preliminary results of an ongoing study by the University of Pennsylvania. However, our expert isn’t convinced (see our analysis below).

The researchers found that people who eat later in the evening for a ‘prolonged period’ have higher levels of glucose and insulin, which is linked with an increased risk of diabetes. They had higher cholesterol too, which is linked with heart disease.

Previous research has shown that sleep loss caused by late eating can lead to weight gain. The new findings suggest that the timing of meals can affect your health regardless of the impact on sleep.

During the randomised trial, nine healthy adults between the ages of 23 and 29 were fitted with sleep monitors and instructed to eat according to a schedule for a period of eight weeks.

The researchers measured the volunteers’ metabolism, energy usage, blood markers, and weight at four points during an eight week observation period.

It was found that those who stopped eating before 7pm had a healthier ‘metabolic profile’ than those who stopped at 11pm, as indicated by changes in levels of glucose, insulin, cholesterol, and triglycerides.

In those who ate earlier, levels of leptin (often called the ‘fat hormone’ because it plays a role in telling your brain when you are full) peaked later in the day. Ghrelin (an appetite stimulant) peaked earlier. This suggests that people who eat earlier feel sated for longer.

Instant analysis

It is difficult to fully assess the outcomes of the study until the paper has been published. Setting aside that, there are questions over the usefulness of its findings.

In clinical terms, would a morbidly obese person have a vastly different outcome by changing their mealtimes rather than, say, going into a calorie deficit? It seems like we may be focussing on minutiae rather than the bigger picture.

Encouraging people to eat earlier in the day when they may enjoy late evening eating may ultimately result in them eating at night in addition to eating earlier in the day. They may just eat more.

Overall, I cannot help but think there are many other lifestyle factors we should be focus on before we get too caught up in hormonal changes and manipulation.

Research score: 3/5

MB