Snacking doesn't always curb appetite and stop us eating more at mealtimes.
It's become accepted wisdom that we need a couple of snacks a day in addition to the meals we eat. And the idea of "six small meals a day" is also touted as the route to weight loss and health.
It's proposed that snacking boosts metabolism and helps us maintain stable blood sugar, as well as helping us eat less by stopping us from getting too hungry.
But do we really need to snack? There's a growing school of thought among nutrition experts that constant snacking may be harming more than it's helping.
The problem may be that snacking doesn't always curb appetite and stop us eating more at mealtimes. The research on this has been patchy over the years; some studies have shown snacking can promote weight loss; others have shown no effect or weight gain when people snack.
The "multiple small meals a day" theory can't really be proven, either. Otago University studies comparing nine meals to three meals a day found that when the kilojoules were the same, the number of meals made little difference.
It may be social or psychological conditioning that makes us think we need to regularly snack. It's morning tea time: I need something to eat. I'm feeling low in energy or bored in the afternoon: I need a snack to pick me up.
Eating might not be the solution in either of these circumstances. We might be better off — especially if we're in sedentary office jobs — getting up from the desk, having a glass of water and sticking to three meals a day. On the other hand, very active people probably need the extra energy they'll get from nutritious snacks.
When it comes to kids, the case for regular snacking can be made more strongly. Younger children have smaller stomachs, and to get in all the nutrition they need in a day, they need to eat more frequently.
It's super important, though, that kids' snacks are nutrient-dense, not just adding extra kilojoules, salt and sugar.
In the UK, research recently revealed children there are getting a third of their recommended daily calorie intake from high-sugar, high-fat snack foods.
It's led to a new campaign to educate parents about what appropriate snack foods are, and recommending no more than two snacks a day of under 100 calories.
Public Health England has blamed what it terms a grazing culture and the erosion of mealtimes as a contributor to the childhood obesity crisis in that country. In New Zealand it is probably not too different — in the most recent diet survey, 40 per cent of children ate chocolate, sweets or lollies once or twice a week and 30 per cent ate potato chips, Burger Rings, Twisties or corn chips.
So what is a healthy snack? Protein and fibre is a good combo, making for satisfying snacks that keep us feeling full. Plain yoghurt and fruit; nuts and seeds; edamame beans; veges and hummus are all good options. As is remembering to consult our hunger before we eat.