People don’t realise just how bad this is for their health. You can eat very well at your main meals but undo all the good by having half a pack of custard creams with your cup of tea or coffee. Yet, if you ask them whether they eat healthily, they will say yes. Snacks are seen as something extra, just a bit of fun that doesn’t really count.

But it very much does count. Tucking into unhealthy snacks means you’re more likely to have a higher weight, more visceral fat (the type stored around our organs), higher blood sugar and poorer insulin responses. These are risk factors for cardiovascular disease and Type 2 diabetes.

However, snacking doesn’t have to be inherently bad. If you change the type of snack you have, the time of day you eat it and how often you snack, it will make a huge difference to your health. These are my top tips.

1. Choose better snacks

I used to eat a mid-morning or afternoon KitKat, Twix or chocolate digestive, as most British people do, thinking there was no real harm in it. It was a daily habit when I was working as a hospital doctor. I now understand how bad it was for my health.

Unhealthy snacks like these – high in calories, sugar or salt – will raise your blood sugar and blood fat levels. In the short term, you will be left hungrier due to spikes and crashes in blood sugar and, eventually, snacking in this way will cause problems like inflammation and weight gain.

Healthier snacks, like nuts, fruit, vegetables, cheese, yoghurt and 80% dark chocolate, do not carry these health risks. While plain nuts are the gold standard, salted are still better for you than crisps.

People might be surprised that some of these healthier snack options are high-fat – nuts, cheese, yoghurt. When I was a junior doctor, we were told peanuts were deadly and cheese was very bad for you because they are high in fat. It’s a misconception that many still believe today. In fact, they’re full of minerals and, more importantly, don’t flood your body with sugar. Research shows that people who eat nuts and cheese have a lower risk of most diseases.

It helps to always carry some of these healthier snacks in your bag – I always try to have mixed nuts or peanuts with me – or prepare some in advance, so you’re not tempted to buy junk when you’re on the go. If you go back to basic whole foods, you can’t go wrong.

2. Snack earlier in the day or with a meal

If you’re having a sweet treat, like chocolate or a biscuit, having it with a meal is much better for you than between meals. Your body copes better metabolically, finding it easier to digest and bring down blood sugar to normal levels.

If you have an unhealthy snack in the middle of a fasting period, it will often stress your system. It’s much harder for the body to get out of its rest phase and kickstart digestion again.

If you are snacking outside mealtimes, the worst time is after your dinner, especially within a few hours of going to sleep. It’s linked to poor gut health, higher blood sugar levels and worse blood sugar and blood fat responses after eating, and even higher levels of hunger the next day.

3. Eat unhealthy snacks less often and in smaller portions

There is no doubt that cutting back on the number of unhealthy snacks you have will benefit your health. Physiologically, if we’re eating between every meal, our bodies don’t get time to rest. Cutting down on the portion size of these snacks is also a good idea.

It helps to put a serving of your snack into a bowl, slow down your pace of eating and wait 20 minutes before going back for seconds, as this is how long it takes to feel full. I know this is tricky, as crisps, chocolate and cakes have been designed to be eaten quickly. You can also bulk up your main meals to fill you up more, to reduce your desire to snack.

Fight against boredom eating. A lot of bad snacking habits happen in the UK because people just want something to nibble on. You have to learn to avoid giving into that, especially when shopping.

However, if you’re a healthy snacker, you don’t need to cut back. As it stands, there’s no evidence that reducing how often you eat the likes of nuts, fruit or yoghurt between meals but not late at night will make a difference to your health.

People of my age group – who grew up on three meals a day and no snacks – will have seen how dramatically our eating culture has changed, while younger people will never have known anything different. Many other countries are much healthier as they resisted this snacking culture.

If there is one thing you want to do to improve your health, start making these healthier snacking choices. It will really improve your overall health and you won’t even have to change your main meals.