It really IS harder to say no to cake when you're fat, finds study of obese volunteers' brains

For some people, turning down a chocolate biscuit or piece of cake seems relatively easy while for others, it's an enormous mental battle.

Now, experts have discovered that people with a higher BMI really do require a bigger shift in brain activity to choose healthy food over their preferred snack.

Researchers from Queen's University in Ontario analysed data from three MRI studies involving 123 participants who indicated what they would prefer to eat in different scenarios.

They compared brain activity patterns displayed when participants chose after being instructed to focus on healthy eating.

Experts have discovered that people with a higher BMI really do require a bigger shift in brain activity to choose healthy food over their preferred snack. Researchers from Queen's University in Ontario analysed data from three MRI studies involving 123 participants who indicated what they would prefer to eat in different scenarios

Analysis revealed that people who were better able to regulate their dietary choices required relatively small shifts in brain states to achieve their goal – and this was highly apparent in individuals with low BMI.

However, participants with a high BMI could not rely on this mechanism and required larger shifts in brain activity to make healthy food choices.

Writing in the Proceedings of the National Academy of Sciences (PNAS) journal the researchers said: 'Over 18 per cent of the global adult population is projected to be obese by 2025, showcasing widespread difficulties in adopting healthy diets.

'We examined how brain states change when making natural and regulated dietary choices in an established food task.

'Individuals with lower weight status could successfully modify their eating behaviours while maintaining similar modes of brain activity.

'Individuals with higher weight status could not rely on this mechanism.'

The team said their findings may help explain why some people struggle with controlling their diet while others do not.

However, they said they are not able to determine whether a difficulty making healthy food choices is what leads to putting on weight, or whether putting on weight leads to changes in the brain that makes it harder to choose healthy options.

WHAT SHOULD A BALANCED DIET LOOK LIKE? 

Meals should be based on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain, according to the NHS

Eat at least 5 portions of a variety of fruit and vegetables every day. All fresh, frozen, dried and canned fruit and vegetables count.

Base meals on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain

30 grams of fibre a day: This is the same as eating all of the following: 5 portions of fruit and vegetables, 2 whole-wheat cereal biscuits, 2 thick slices of wholemeal bread and large baked potato with the skin on

Have some dairy or dairy alternatives (such as soya drinks) choosing lower-fat and lower-sugar options

Eat some beans, pulses, fish, eggs, meat and other proteins (including 2 portions of fish every week, one of which should be oily)

Choose unsaturated oils and spreads and consuming in small amounts

Drink 6-8 cups/glasses of water a day

Adults should have less than 6g of salt and 20g of saturated fat for women or 30g for men a day

Source: NHS Eatwell Guide