What time is breakfast?
Breakfast! They say that it’s the most important meal of the day, but could when you eat, rather than what you eat, be a way to manage your weight, and overall health? Dietician and PhD student Shantel Lynch from Surrey University is asking exactly this, and she spoke to Katie about the concept of time restricted eating. First up though, with Katie being pro-breakfast and Adam anti-breakfast, who is correct? Katie put this to Shantel...
Shantel - That's a complex question in the sense that everyone's slightly different. So our genetics may predispose us to be either a morning type, so like a morning lark, or a night owl. And that may actually influence our decision as to whether we want to eat in the morning versus whether we went to eat later on in the day. Now, we don't know just yet whether there's a right or wrong answer in terms of when we should be eating, but we do know that during the course of a day, there are some variations in how we process our nutrients. For example, if you have a meal that contains carbohydrates, our bodies will break that down to glucose or sugar. And we know that if you have this same meal in the morning, versus if you have that same meal in the evening, our bodies find it a bit more difficult to manage it in the evening time.
What happens is that we have a higher peak in our blood sugar levels if we eat that same meal in the evening and that peak in blood sugar stays higher for longer. And if you have elevated blood sugar levels for a long time, we know that this perhaps can predispose you to things like type two diabetes. So we know there's variations in how our bodies process nutrients, but we don't know exactly the mechanisms behind it.
Katie - OK, so you're looking specifically at the time of day you're time restricting eating to, as it were. But in general - full disclosure, I've actually been trying time restricted eating for a few weeks. What's the evidence it's doing me any good?
Shantel - The evidence base isn't huge at the moment. There are pilot studies, which are small-scale studies in small numbers of individuals. And this research is coming up with some positive results that restricting your eating window is having positive effects on your weight, the way that we process our nutrients, the way we managed our blood sugar levels, how our body fat is distributed, perhaps things like our blood pressure as well. So there is some really positive evidence out there. However, they aren't large studies and there's not a lot of them. So it's too early to say for sure whether it's definitely a good thing for everyone, or for the majority. We do have to wait for some more research to come out.
Katie - And do we know much about whether eating later or earlier is better, at this stage?
Shantel - In humans, there is some emerging evidence that perhaps eating early in the day may be better for you, but these studies are in small supply and in small groups of individuals. So because there are some promising results that perhaps eating earlier in the day may actually help you to manage your weight better, it may help you manage your blood sugar levels better, there is some new research coming out trying to explore this a lot more. We do hypothesize that actually eating early in the day will be superior, but we don't know for sure until we've kind of got those results through. Some of the research that I'm doing is actually exploring the chronotypes of my participants as well, so that we can actually see, does this have an impact on when you should be eating? And should we be tailoring dietary advice to whether you're an early type or an evening type? Or does it not make a difference at all?
Katie - Are there particular groups of people that you would be interested in trying this time restricted eating diet on?
Shantel - The group of individuals that I'm looking at in this study are those who are at higher risk of developing type two diabetes. Some of the animal evidence showed that time-restricted eating may actually be protective against obesity and type two diabetes. So does this translate to humans as well? Does it have an effect on what we know are risk factors for type two diabetes like your weight, like how you manage glucose? Does this work for this group of individuals?
Katie - Do we have to be a little bit careful here Shantel, because if anyone is doing any diet, I guess you have to control for perhaps the possibility that we might just be thinking more about food and therefore eating a bit less anyway?
Shantel - There's so many things that you have to think about. Simply by saying you're putting someone on a diet, it may mean that even if they are given the eight hour window, they'll probably just try to eat as much as they can in that eight hours. We do need to be careful and we do need to be mindful in that sense, which is why we're looking at a variety of different outcomes, how it affects social interactions, psychological wellbeing, whether this type of eating leads people to overeat because they're actually told they've only got eight hours to eat? Does it affect how they feel because they're missing out on social events, due to not being able to eat at certain times? There's lots of things to consider. So there's not just one clear cut answer here.
Katie - As a dietician, is time restricted eating a diet you would recommend?
Shantel - We're not at a stage where we are recommending it to all different groups of individuals, because you have to remember that if you've got a particular health condition, it may not actually be appropriate to fast for long periods of the day. We need to look more at really does this diet work? Who does it work in? What impact does it have on people's lives? There's no point recommending a diet that people can't stick to in the long run. And then we can then say, is it realistic to get this advice? And what groups of people do we want to give this advice to? But as this evidence starts to come through, we are drip-feeding it into advice and supporting people with this type of diet if they want to do it. But I would say before doing anything like this, please do speak to a healthcare provider and check that it is actually safe to do so.