DO I smell?

Undoubtedly. All humans have their own idiosyncratic tincture, often so faint that it can only be detected by those who rub up against us. A few unfortunates give out signals at 6ft, but whether or not these are deemed unpleasant depends on cultural norms as much as wind speed.

Incidentally, the female Emperor moth (Eudia pavonia) puts out a pheromone that can be picked up by a male 6.8 miles away.

Why do I smell?

There must be some evolutionary advantage to smelling or it would have been banished from the gene pool. It's probably got something to do with keeping the flies off your tucker or tracking down your partner in the dark.

Perhaps it encourages us to mate with the same species (Desmond Morris can fill you in with the details here). Some couples admit to finding each other's scent a turn on, but then sex has a remarkable capacity to make erstwhile vile smells and tastes alluring (if only for 10 minutes.)

I meant, what makes me smell?

Sweat itself is largely blameless, unless you've pigged out on garlic, onions, curry and alcohol (hence the Sunday-morning stinker). It's the colonisation of sweat that's been hanging around for several hours by chemical-releasing bacteria that causes the problem.

Sweat tends to congregate in areas where it can't escape from in polite society (genitals, nipples and armpits). These areas are also blessed with a special type of sweat gland, the apocrine gland, which produces sticky, milky fluid containing fats and proteins. These glands become active in adolescence and their fluid is said to be pheromonal.

Unfortunately, it's also a bacterial feast. The other type of sweat gland (eccrine), is most concentrated on your forehead, palms and soles. Socks, gloves and woolly pom-pom hats provide an enclosed, airless environment for sweat-rotting bugs.

Why sweat?

The average torso boasts two million sweat glands which chum out more than three litres every 24 hours (2.1mls a minute). Its function is to control body temperature and stop you overheating. Most of it evaporates easily. Hot weather, alcohol, exercise, obesity and agitation up the production and humid conditions slow down evaporation.

Some people sweat buckets even when they are cold, sober, slim, stationary and stress-free. Although upsetting, this isn't harmful unless it is combined with other symptoms which suggest something else is responsible - for example weight loss, weakness, trembling, increased appetite and bulging eyes (over-active thyroid gland or orgasm), night sweats, cough and weight loss (infection or tumour) or irregular periods (menopause).

How can I try to control my BO?

The text-book advice to wash all over and change your pants, socks and any skin-hugging clothes every day seems condescending in the extreme. However, only a third of men wash behind their foreskin every day, while the majority are either too lazy or actually enjoy the smell of their own smegma.

Sadly, some people with scrupulous personal hygiene still seem to sweat or smell excessively, and accusing them of skimping on the soap isn't particularly helpful. Others lack the mobility to reach under their armpits or perhaps can't afford the hot water.

Using an anti-bacterial or antiseptic soap, particularly in your apocrine areas can help, but avoid over-washing as it can remove healthy skin bacteria and make the problem worse. It is a good idea to dry carefully after bathing and pamper yourself with talcum powder as bacteria prefer moist skin.

Tight or synthetic clothes and night garments are out. Go for baggy cottons that allow the sweat to evaporate and sleep in the raw. Shower promptly after exertion, wear cotton socks, rotate your shoes round, go easy on alcohol and try not to pile on the pork.

What about a deodorant?

Deodorants alone just mask the smell and don't cut down on sweat rot. Choose wisely; the heady mix of BO and cheap cologne is worse than BO alone.

Go for one containing antiperspirant, too. These work by either stopping the bacteria from rotting or, rather perversely, by preventing the sweat from evaporating and holding the sweat and smell in.

Experiment with a few to find which type and method of delivery suits you best. Some can cause irritation and you would be unwise to apply them to broken skin or your genitals.

What if this doesn't work?

Your doctor may prescribe a strong antiperspirant containing aluminium chloride. This reduces the amount of sweat you produce, but tends to cause skin irritation.

In very severe cases, the sweat glands can be surgically removed from under your arms. Unfortunately, this hurts and the sweating tends to return after a few months.