Worried you smell bad? This is the everyday food you should stop eating - and the VERY unexpected ingredient that will banish body odour

The smell of your body is so unique to you that it can be used to tell people apart. Trained sniffer dogs, and even specially designed machines, can identify you just by your body scent.

That's because your skin releases a mix of scent molecules that's like a personal chemical signature. Even identical twins, who share almost all the same DNA, have their own unique scents.

This is because your personal odour profile is influenced by all sorts of factors – from what you eat to your age, genetics, and the medications you take.

For instance, being on the Pill changes levels of oestrogen and progesterone, which can subtly shift your mix of scent molecules. This doesn't make your body odour stronger or worse – just slightly different.

Other medication can cause stronger or more noticeable changes but only in some people – for example, metformin (for diabetes).

Your personal smell, then, is constantly changing. This is different from body odour. While your personal scent is usually subtle, body odour is stronger and happens when sweat mixes with bacteria – it's what we notice when someone smells 'sweaty'. Sweating is your body's way of cooling you down. As sweat evaporates from your skin, it carries heat away from your body, lowering your core temperature.

The sweat itself doesn't smell as it's mostly water and salt. The smell is caused by the mix of bacteria naturally present on your skin feeding on fats and proteins also found in sweat. The resulting by-products are what produce the smell, or body odour.

Ever wondered why body odour tends to focus around the armpits? It's because the sweat glands here produce sweat that's richer in fats and proteins than that from the sweat glands around other parts of your body, providing a feast for odour-causing bacteria.

How smelly the resulting odour is depends on what type of bacteria you have – some can be more stinky than others.

That classic armpit BO smell – the whiff you get in a football dressing room – mainly comes from common skin bacteria such as Corynebacterium, along with Staphylococcus and Cutibacterium, according to a 2013 review in the journal Trends in Microbiology.

Deodorants can help, mainly by reducing the bacteria that cause body odour, often using antimicrobial ingredients such as alcohol. Some also contain fragrance to mask the smell, and a few may alter skin pH slightly which deters bacteria growth.

But you can also manipulate your body odour by changing your diet – although, interestingly, most of the research on this has been on men, not women (possibly because we tend to think of men as being less fragrant than women).

In one key study, published in 2017 in the journal Evolution and Human Behavior, a group of 43 men were given fresh T-shirts to wear for 24 hours.

Women were then asked to sniff the tops, and to rate the odour according to factors such as attractiveness and intensity, and describe whether the smell was more floral, fruity, or meaty.

The results were interesting: the sweat from men who ate more fruit and veg was rated as more pleasant and attractive (the higher the fruit and veg, the nicer the sweat).

In evolutionary terms, this is probably because this scent reflected a good diet and was a sign of good health.

This tallies with other findings on garlic. For, despite its reputation for causing bad breath (which it does for most of us, depending on how much you eat), it may actually make your body odour smell more pleasant, according to a 2016 set of studies published in the journal Appetite.

When women rated the underarm scent of men after they had eaten garlic (either two or four cloves) or had none, the men's body odour on the days when they ate four cloves was rated more attractive and pleasant, and less intense than on the days they had no garlic.

So how could it make the men's body odour nicer?

Garlic has antimicrobial and antioxidant properties and the researchers thought it might have reduced the skin bacteria responsible for breaking down sweat into smelly compounds. They also suggested its antioxidant effects could change the chemical composition of sweat, leading to a cleaner, more pleasant odour.

You might have heard the term 'meat sweats' – the description given to excessive sweating after someone has eaten a lot of meat.

These are real, but it's not just about sweating after a big steak dinner.

Large portions of any kind of food can increase your core temperature slightly, simply because your body is working harder to digest and absorb it. That can lead to a bit of sweating.

But something else is also going on: there's some research to suggest that eating a lot of red meat may affect the way your sweat smells, and actually make you smell less appealing.

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A 2006 study published in Chemical Senses found that when men stopped eating red meat for two weeks, women rated their body odour as more pleasant and attractive.

The researchers from Charles University in Prague thought that red meat might change the composition of sweat, making it richer in fat and protein by-products – that skin bacteria break down into smellier compounds.

Meanwhile, spicy foods can make you sweat more, because of a compound called capsaicin, found in chillies and hot spices which gives them their heat.

Capsaicin tricks your body into thinking it's hot, triggering your cooling system and making you sweat – and the more sweat there is, the more food for the bacteria that might make you smelly.

Sometimes excessive or persistent body odour can have an underlying medical cause. For instance, an acetone-like smell in your sweat might be a sign of poorly controlled diabetes. Some conditions or life stages can make you sweat more, and while sweat itself doesn't smell, it can make body odour more likely.

For some people who sweat excessively, it's down to a condition known as hyperhidrosis (which can be genetic). The menopause, an overactive thyroid, and stress and alcohol can all cause sweating.

If body odour is affecting your day-to-day life, it's worth having a chat with your GP.

Apart from keeping an eye on my caffeine intake, what can I do diet-wise to help me sleep better?

If you're looking for foods that might help you sleep, there's some interesting (if early) research behind tart cherry juice – from a specific kind of cherry known as a montmorency – and kiwi fruit.

Tart cherry juice naturally contains melatonin, the hormone that helps us feel sleepy, and a few small trials have found that drinking it during the day or before bed can help people (especially those who struggle with sleep) nod off a bit sooner and sleep a bit longer.

It's a similar story with kiwi fruits – a 2011 study showed that when people ate two kiwis an hour before bed, it was easier to drift off and stay asleep. Kiwis contain serotonin, a building block for melatonin.

However, these effects are fairly modest. When it comes to what you eat, what matters most for sleep is your overall diet.

There's some evidence that not getting enough fibre or protein affects sleep quality, possibly because fibre slows digestion, which helps steady blood sugar, and it feeds the gut microbes linked to brain and immune function – both may influence sleep.

Meanwhile, protein provides tryptophan, an amino acid needed to make both serotonin and melatonin. I'd focus on eating plenty of whole grains, fruit, veg, and healthy fats – the kind you find in a Mediterranean-style diet, which is linked to better sleep quality.

As well as managing your caffeine intake, remember that while alcohol might help you nod off at first, it tends to disrupt your sleep later in the night, leaving you feeling groggy in the morning.