In terms of diet, humans can best be described as “omnivorous opportunists”. We don’t have the multichambered stomachs that help herbivores subsist on grass, but we have more molars than the average carnivore. Maybe it is no surprise, then, that we love to snack: we don’t need to graze, but neither are we into eating a whole gazelle, then sleeping for 20 hours.
The trouble is that things have moved on since we were grabbing a handful of berries here and an unwary rabbit there; these days, we are rarely more than a minute away from a couple of custard creams or a banana. Is our inbuilt inclination to snack doing us irreparable damage, or do all those calories even out in the end? And if you work in an office full of feeders, what is your best course of action?
Martin MacDonald, a clinical nutritionist and the founder of Mac‑Nutrition Uni, says: “The biggest potential downside of snacking is that the foods people most commonly choose are not those that promote good health. That means that regular snacking on top of meals can easily lead to overconsumption of calories and unhealthy fat gain.”
That is the simple answer; but if you are sticking rigorously to healthy foods or your recommended daily calorie allowance, does it matter when you eat them? Does eating smaller main meals and a few snacks, for instance, keep your metabolism more fired up than eating an entire roast chicken and then going for a lie-down?
“There’s a train of thought that comes from a lot of observational research that eating smaller meals or snacks more frequently is better for our health,” says MacDonald. “This just isn’t the case, however – we have a significant amount of evidence from controlled trials that contradict the observational studies.”
It is true, for instance, that your metabolism increases after you eat, because of what is known as the thermic effect of food – the energy it takes for your body to digest, absorb and metabolise it – but this doesn’t mean frequent snacking will keep you lean. Eat small meals often and your metabolism will increase by small amounts after each one, but feast once or twice a day and it will go into high gear after each meal, meaning that the effect balances out overall.
On the flipside, there is no evidence to suggest that eating frequently is bad for health in and of itself. “I’ve heard claims made about the body ‘needing a rest’ between meals,” says MacDonald. “But this only becomes an issue when an individual is overconsuming. A good way to help understand this is by thinking of the body as a bucket with a hole in it. When we eat a large meal, it’s like putting a big ice cube in the bucket – the period after it melts and the water trickles out is called the ‘postabsorptive state’. If you eat smaller meals more often, the smaller cubes melt and leave the bucket faster, but you’ll also be going back to the digestive state sooner, because you’re eating more frequently.”
One caveat here is that there is some research suggesting that leaving a decent gap between your last feed in the evening and your first one the next day may have beneficial effects on blood pressure and insulin sensitivity. More research is needed, but if you are going to cut out snacks at any time of day, the late-night ones are probably the place to start. Something else to bear in mind is that when people eat less often during the day, they tend to consume fewer calories, even if they aren’t counting them.
But what if you are an unrepentant snacker, either because it is tough to make time for bigger meals or because you need the occasional pick-me-up? “It does seem that people can ‘train’ themselves to snack less simply through practice,” says MacDonald. “This is probably possible for a number of reasons, such as our gut appetite hormones making us hungry at our ‘usual’ eating times – but it’s only really necessary if you are unable to eat good snacks.”
If you can plan ahead and make sure you have access to whole, unprocessed foods, there is nothing wrong with snacking. “Mixed nuts and whole fruit or Greek yoghurt with berries are two very good options,” says MacDonald. “The latter is probably better if you would like to lose or maintain weight more easily. There are often claims that snacking on nuts will lead to
fat gain due to their energy content, but that’s not supported by the research – and nuts contain a diverse range of nutrients that are beneficial for health. Opting for whole fruit is probably better than dried fruits or juices, as it’s less easy to overconsume calories.”
This all takes a bit of effort, of course, but that is part of the point. When snacking is not as simple as just grabbing a Mars bar, you will probably start to wonder whether you need to do it quite so often.