It's not about how much you sweat
"The sweat doesn't really produce an odor itself. It's the bacteria that we have on our skin," says Dr. Constantine George, an internal medicine specialist and founder of Hygeia Health & Wellness in Las Vegas. "We're a petri dish walking on two legs. When bacteria have a wet or moist environment, they tend to thrive and grow. And when bacteria thrive and grow, they can produce their own odors."
There are two types of sweat glands. Eccrine glands are the most common, and can be found throughout the body, secreting sweat directly onto the skin. Apocrine glands can be found in areas like the armpits and groin, and dump their sweat into hair follicles first.
Unfortunately, while these glands create sweat that mixes with bacteria to make us smelly, we kind of need 'em. "They control your body temperature," says Dr. George. "So if you're out running or jogging in the summertime, it can get really hot and your body has to somehow cool down. So by releasing sweat, you have an evaporative cooling effect. So you don't get high internal body temperatures."
And you can probably infer that if your body isn't able to cool itself off, bad things happen. "You can have massive seizures and die," confirms Dr. George. Massive seizures and death are bad!
So we've all got bacteria. Why don't we all smell the same?
One of the big reasons is diet, which makes a lot of sense, given the whole "you smell like what you eat" cliche. Wait, is that how it goes? As Dr. George explains, "Let's say you eat garlic, onions, and spicy foods that have odors. That can be a problem." As your body digests these foods, compounds are produced and released through the pores of the skin, and all of a sudden you smell like a refrigerator crisper that hasn't been cleaned in months.
Shared bacteria can explain why a family or people living together in a household may have a common smell. "If you and your spouse have a child… you're holding the kid, cuddling the kid, bathing the kid, so the child will be contaminated with the same types of bacteria as well… so theoretically you should all have the same type of smell."
Let the record note that Dr. George said "quote, unquote" after the word "contaminated," meaning it's not a bad thing. So don't be ashamed of having all that bacteria, which can spread from home to home if a family moves. "Whenever you touch something -- the door handles, the kitchen counters, everything -- you're spreading bacteria all over the house," he adds. "Therefore, we get that same smell."
There's an even more obvious answer: Some people are just dirty
Other explanations for why human beings smell different from each other include hygiene and health. Consider one's lifestyle. People who are dirtier than others are going to have more bacteria on their bodies -- especially if they don't shower often. Money and income can be issues if cleaning resources and products are scarce, most dramatically in extreme situations like homelessness.
People who are overweight may have folds in their skin, which are breeding grounds for bacteria. This is common with diabetics -- whose problems with smell can go beyond having a few extra pounds. "If they have higher-than-normal blood sugar, there's a condition called diabetic ketoacidosis -- or DKA," says Dr. George. "And those patients tend to have more of a fruity smell to them."
Wait a minute. A fruity smell?
"If you're not controlling the diabetes well, your body can't utilize sugar as much. You're going to break down fats," explains the doctor in describing DKA. "And that can produce distinctive odors."
There's also a condition called (yes, this is a real one) maple syrup urine disease that's generally found in kids. "Kids can often have underlying liver disorders where they are missing enzymes to help them metabolize certain food products," Dr. George says. "So their urine smells like maple syrup -- believe it or not."
But let's not get sidetracked. The main culprit is bacteria on the skin, and the main causes are diet and hygiene.
Asking for "a friend," what's the best way to get rid of body odor?
First things first. Shower at least once a day. Maybe twice. "You don't want to do it excessively," advises Dr. George. "Because your body still needs to retain natural oils for lubrication and moisturizing." When lathering up, avoid soaps heavy on chemicals, dyes, and fragrances. "Just because it has a nice smell, doesn't mean it cleans you any better. At the end of the day, most soaps do the same job."
After showering, Americans in particular might consider rubbing on deodorant under the arms. "Antiperspirants stop the liquid from forming in the armpits," says Dr. George. "Deodorants tell the bacteria not to break down so quickly, therefore reducing the odor."
Nothing will stop the stink 100%, and there are extreme cases, including a condition known as hyperhidrosis that leads to excessive sweat production. So if basic hygiene fails, patients may turn to Drysol, a prescription-strength antiperspirant, or an oral medication called glycoperate. Botox injections are also an option to temporarily block the nerves that stimulate sweat glands. As a last resort, those nerves can be surgically removed.
But be warned. "If the patients can't sweat, they have to stay indoors and monitor their temperature," Dr. George points out. "They can't go outside in the summertime and jog. When they overheat, they have no way of evaporative cooling."
At least it won't be as bad when they're sitting next to me on the subway.