Nuts have long had a reputation as diet wreckers—too fatty, too calorific, too moreish. But new research is turning that idea on its head.

A recent study discovered that young adults who consumed a breakfast featuring 50g of walnuts not only felt more alert but also excelled in memory and reaction tests later that day.

Meanwhile, a review of weight-loss research indicated that nuts included in calorie-controlled diets didn’t impede results—in fact, some participants who included nuts lost more weight than those who did not.

It’s not the first time nuts have impressed scientists.

Over the years, research has associated nuts with reduced risks of diabetes, heart disease, and even depression, along with improved fertility and enhanced brain function in later life.

Despite decades of supporting evidence, nuts still aren’t prominently highlighted in public health initiatives, and many individuals remain concerned, fearing that the calories might overshadow the advantages.

Experts assert that the opposite is true. Eating a handful daily can provide a beneficial mix of protein, fiber, and healthy fats that not only satisfies hunger but also contributes to long-term health protection.

To learn which types offer the most advantages and the ideal quantity to consume, we consulted with nutritionists Grace Kingswell and Dr. Emma Derbyshire.

Nuts have long had a reputation as diet wreckers—too fatty, too calorific, too moreish. But new research is turning that idea on its head

Why nuts won’t make you fat 

At first glance, it makes sense to be cautious. A small handful of almonds contains more than 150 calories, while Brazil nuts are among the fattiest plant foods you can buy.

But research shows those calories don’t behave in the same way as the empty kind found in biscuits or crisps.

Studies by the US Department of Agriculture have shown that we don’t absorb all the fat in nuts. Around a fifth of the calories in almonds and walnuts never make it into the bloodstream, because the fat remains locked inside their fibrous cell walls and passes straight through the digestive system.

‘Nuts are incredibly nutrient-dense, but the body doesn’t utilise every calorie they contain,’ says nutritionist Grace Kingswell. ‘That’s why they don’t have the same impact on weight gain as other high-fat foods.’ 

Their unique mix of protein, fibre and unsaturated fat also keeps hunger in check and stabilises blood sugar—meaning people are less likely to reach for snacks later.

A review of weight-loss trials last year even found that participants who included nuts in their diets sometimes lost more weight than those who cut them out.

In other words, far from being diet-wreckers, nuts can actually support weight control when eaten in sensible portions—roughly 30g a day, or a small handful.

Grace Kingswell is a nutritional therapist specialising in fertility, using diet, lifestyle and supplements to support her client’s health

More than just a snack

Once the weight myth is set aside, the range of benefits is striking. 

‘Nuts are a great source of fibre, vitamin E, antioxidants and minerals—but more importantly, they work on multiple systems in the body at once,’ says nutritionist Grace Kingswell.

Vitamin E, abundant in almonds and hazelnuts, is a powerful antioxidant that helps protect cell membranes from damage. 

Higher intake from food has been linked in several large studies with slower age-related cognitive decline. 

Walnuts and pecans, meanwhile, are high in polyphenols that dampen inflammation, a driver of heart disease and diabetes.

There are reproductive benefits too. A Spanish clinical trial found men who added two handfuls of mixed nuts to their diet every day for 14 weeks improved sperm count, motility and morphology. 

Other research suggests women who eat nuts regularly are less likely to experience problems conceiving, possibly because of the role omega-3 fats and selenium play in hormone balance.

On top of this, regular nut consumption is associated with lower blood pressure, reduced risk of type 2 diabetes and even a modest lift in mood—thought to be due to their effect on neurotransmitters like serotonin.

Not all nuts are created equal, though. From the brain-boosting power of walnuts to the thyroid-friendly punch of Brazil nuts, each type brings something different to the table…

Dr Emma Derbyshire said the number of people who are nutrient deficient is a ’cause for concern’ and is urging everyone to get back to the basics of snack on nutrient-dense foods like nuts 

Walnuts boost brainpower

Walnuts are especially rich in omega-3 fatty acids, protein and polyphenols. 

A University of Reading study found that when young adults added just 50g of walnuts to breakfast, they enjoyed faster reaction times and sharper memory throughout the day. 

Omega-3 fats are already thought to help shield against Alzheimer’s disease and stroke, and the Reading trial was the first to show even a single serving of walnuts could deliver a measurable mental boost.

Brazil nuts pack a punch

Brazil nuts are one of the richest sources of selenium, a key nutrient for thyroid health. 

Just three provide a full day’s requirement—but Kingswell warns against overdoing it, since too much selenium can be toxic. 

Despite being high in saturated fats, Brazil nuts also contain magnesium, copper and phosphorus, and a small study even suggested a single monthly serving could lower cholesterol faster than statins. 

Public health nutritionist Dr Emma Derbyshire adds that older adults in particular often fall short on selenium, making Brazil nuts a useful addition in moderation.

Almonds help the gut

Almonds stand out for fibre, with a 30g serving providing around 4g—helping boost gut health, immunity and digestion. 

They’re also rich in vitamin E, which has been linked to lower risks of heart disease and even some cancers, though more large-scale research is needed to confirm these effects. 

Nut butters under scrutiny

Nut butters have surged in popularity. Almond, hazelnut and pistachio butters are marketed as healthier swaps for peanut butter, and indeed they provide protein, fibre and good fats. 

But not all spreads are equal. ‘There are a lot of nut butters on the market that are full of palm oil or sugar,’ says Kingswell. 

‘It’s important to look for one that’s 100 per cent nuts, with maybe just a pinch of salt.’ 

Whole nuts, she adds, remain slightly higher in fibre and may be better for blood sugar control.

Because nut butters are so concentrated, it’s easy to eat far more than you realise—a tablespoon can contain the equivalent of several handfuls of nuts, meaning calories mount quickly. 

Kingswell also notes that peanuts in particular are prone to mould, which can produce toxins linked with immune problems and, in rare cases, cancer. 

Brazil nuts should also be limited to avoid excess selenium.

Easy ways to add them in

Still, for most people, the benefits far outweigh the drawbacks. 

Dr Derbyshire says: ‘Nuts are great as they are, but they can be paired to further improve nutrient absorption and balance.’ 

Pairing them with berries or oranges, she explains, enhances the iron absorption from nuts, while sprinkling them on top of yoghurt can provide ‘an array of complementary amino acids, known as protein synergy.’

Kingswell added that activating nuts—which involves soaking them overnight and then slowly dehydrating them in the oven—can make the nutrients more bioavailable and easier to digest. 

Because they are naturally low in carbohydrates but high in fibre and healthy fats, nuts also make an ideal snack for people looking to manage blood sugar or improve their diet.

‘Despite decades of diet advice and campaigns, we are still not better off when it comes to our nutrition and this includes brain and immunity nutrients,’ she says. 

‘We need t get back to the basics of snackin on and cooking nutrient-dense fresh foods and minimising sugary, fatty snacks. 

‘In an ideal world, people should be able to get all the nutrients they need from their diets.’

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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