Many of us try to eat more fruits and vegetables and less ultra-processed food. But why is sticking to your goals so hard?

High-fat, sugar-rich, and salty foods are simply so enjoyable to eat.

In wealthy modern societies we are bombarded by advertising which intentionally reminds us about the sight, smell and taste of calorie-dense foods. And in response to these powerful cues, our brains respond just as they're designed to, triggering an intense urge to eat them.

Here's how food cravings work and what you can do if you find yourself hunting for sweet or salty foods.

What causes cravings?

A food craving is an intense desire or urge to eat something, often focused on a particular food.

We are programmed to learn how good a food tastes and smells and where we can find it again, especially if it's high in fat, sugar or salt.

Something that reminds us of enjoying a certain food, such as an eye-catching ad or delicious smell, can cause us to crave it.

The cue triggers a physical response, increasing saliva production and gastric activity. These responses are relatively automatic and difficult to control.

What else influences our choices?

While the effect of cues on our physical response is relatively automatic, what we do next is influenced by complex factors. Whether or not you eat the food might depend on things like cost, whether it's easily available, and if eating it would align with your health goals.

But it's usually hard to keep healthy eating in mind. This is because we tend to priorities a more immediate reward, like the pleasure of eating, over one that's delayed or abstract – including health goals that will make us feel good in the long term.

 Stress can also make us eat more. When hungry, we choose larger portions, underestimate calories and find eating more rewarding.

Looking for something salty or sweet

So what if a cue prompts us to look for a certain food, but it's not available?

 Previous research suggested you would then look for anything that makes you feel good. So if you saw someone eating a doughnut but there were none around, you might eat chips or even drink alcohol.

But our new research has confirmed something you probably knew: it's more specific than that.

If an ad for chips makes you look for food, it's likely a slice of cake won't cut it – you'll be looking for something salty. Cues in our environment don't just make us crave food generally, they prompt us to look for certain food "categories", such as salty, sweet or creamy.

Food cues and mindless eating

Your eating history and genetics can also make it harder to suppress food cravings. But don't beat yourself up – relying on willpower alone is hard for almost everyone.

Food cues are so powerful they can prompt us to seek out a certain food, even if we're not overcome by a particularly strong urge to eat it. The effect is more intense if the food is easily available.

This helps explain why we can eat an entire large bag of chips that's in front of us, even though our pleasure decreases as we eat. Sometimes we use finishing the packet as the signal to stop eating rather than hunger or desire.

Is there anything I can do to resist cravings?

We largely don't have control over cues in our environment and the cravings they trigger. But there are some ways you can try and control the situations you make food choices in.

Acknowledge your craving and think about a healthier way to satisfy it. For example, if you're craving chips, could you have lightly-salted nuts instead? If you want something sweet, you could try fruit.

Avoid shopping when you're hungry, and make a list beforehand. Making the most of supermarket "click and collect" or delivery options can also help avoid ads and impulse buys in the aisle.

At home, have fruit and vegetables easily available – and easy to see. Also have other nutrient dense, fiber-rich and unprocessed foods on hand such as nuts or plain yoghurt. If you can, remove high-fat, sugar-rich and salty foods from your environment.

Make sure your goals for eating are SMART. This means they are specific, measurable, achievable, relevant and time-bound.

Be kind to yourself. Don't beat yourself up if you eat something that doesn't meet your health goals. Just keep on trying.