What’s the science behind dumping junk food?

A woman orders a burger

Whether we call it junk food, fast food, takeaways or ‘treats’, everyone in the UK eats food that is tasty but low in nutritional value

Only 4% of Brits claim they never eat junk food. For some people, junk food is of the sugary variety – soft drinks such as cola or milkshakes, sweets, biscuits, cakes and chocolate. For others, it’s salty, savoury food that we find hard to resist: think burgers, crisps, chips, fried chicken, hot dogs and pizza – although these savoury foods are often surprisingly high in sugar, too.

What is junk food and why should we cut down?

What scientists consider to be junk food can include a range of different things and may vary across ages and cultures but most of this food has the following in common:

  • High in fat, salt and/or sugar
  • Highly palatable (easy and tasty to eat)
  • Ultra-processed – this is still a new area of research, despite highly processed food being around for at least half a century. But it typically includes food made using industrial equipment that alters the original food by breaking it down and combining it again, often with artificial preservatives and other additives that that you don’t find in a typical kitchen.

Junk food can be very tasty largely because of the fat, sugar and salt it contains. When we eat junk food often and in large amounts, we can easily eat too much of it because it tastes good – not because we’re necessarily hungry.

We also live in a world where it’s hard to say no to junk food because it’s widely advertised, readily available and often cheap to buy.

Because junk food typically contains a lot of calories, it can contribute to weight gain, and we have strong evidence that living with overweight or obesity can increase your risk of developing at least 13 types of cancer. That’s why:

  • limiting fast food
  • limiting sugary drinks
  • eating a diet high in wholegrains and other plant foods

are all in our Cancer Prevention Recommendations. These Recommendations are guidance produced and checked by scientific experts to help everyone – individuals and populations – reduce their risk of cancer.

Surely people can’t just give up junk food?

Just as there are no super foods when it comes to cancer prevention (and certainly none when it comes to curing cancer), there are no single junk foods that are worse for us than others. It’s a pattern of eating, moving and living that does the most when it comes to reducing our risk of developing cancer and other diseases.

Committing to giving up our favourite – or even all – junk food for a period of time can help us realise what and how much we eat, as a way towards gradually making longer lasting changes.

What is Dump the Junk?

Dump the Junk campaign

Our fundraising campaign encourages people to raise money for World Cancer Research Fund by cutting out or cutting down on junk food for 1 month. You can ask people to sponsor you for every day without junk food, or pay a “fine” every time you give in to temptation.

But the benefits of changing our eating habits, with support, last much longer than 1 campaign. That’s why, alongside Dump the Junk, our Activ8 Plan is an 8-week challenge that will help you bed down changes – not just eating habits but shopping, cooking and travelling too – that could have long-term – even lifelong – benefits to your health.