Sweating should help you lose weight, right? After all, sweat is mostly water, and before you sweat, that water is inside your body.
If you’ve ever hauled buckets while gardening or camping or moved a load of wet towels to the dryer, you know that water is heavy. If the process of sweating moves water from inside your body to the surface of your skin, where it evaporates, your body should lose a few pounds, right?
Not so fast.
Take a look at the last paragraph again. Sweat is made primarily of water (other components include lactic acid, urea, and trace amounts of minerals like sodium and potassium). When we sweat during a workout or on a hot day, we replenish that water soon afterwards. If we don’t drink water shortly after we sweat, we will become dehydrated – dangerously so.
Sweating during a workout may help some fitness buffs feel motivated and confident, but on a physical level sweating to lose weight does not work and can lead to dangerous imbalances in the body.
The human body constantly seeks balance. The process of achieving this balance is called homeostasis. Sweating is how your body maintains its temperature. If your brain detects that your core temperature has increased, it sends a message that activates your sweat glands. The water in your sweat is hot because it has been inside your overheated body, so when this water exits your body through its pores and then evaporates, the body’s core temperature drops back to the equilibrium your body wants.
Your body also maintains its water balance through homeostasis. If you drink too much water, your body releases the excess by urinating. If your body’s water supply is depleted – through sweating, for example – you will become dehydrated. While sweating is a natural process that benefits your body, you must drink water soon after you sweat. If you are truly giving your body the water it needs, the water you drink will weigh the same as the water you lost by sweating.
It’s true that some athletes – including MMA fighters, wrestlers, and boxers – induce sweating before they weigh in to qualify for their events. However, immediately after they qualify, they replenish their body’s water balance before they compete. Even so, this practice can be dangerous because it pushes the body’s water balance to extremes.
Others who believe in sweating to lose weight manipulate parts of their environment in order to sweat more.
Remember that the purpose of sweating is to move overheated water from inside your body to its surface, where the water will evaporate. For this process to work, the body’s surroundings need to be at least a little bit cooler than the body’s core temperature. If sweat is trapped on the skin by heavy clothes, it doesn’t evaporate, and the body won’t cool down. If you sweat in a room or in an outdoor space that is hotter than your body’s core temperature, your sweat will not evaporate, and your body will not achieve the healthy balance that it seeks. If sweat remains on your skin and the body doesn’t cool down, your body will secrete more sweat. Interfering with your body’s natural cooling process can cause dehydration and heatstroke.
Manufacturers of neoprene belts, also known as waist-trimmer belts or slimming belts, insist that these belts promote weight loss by increasing sweating in the body’s core. In fact, not only do these belts not promote weight loss, but they don’t even cause increased sweating.
Neoprene is a non-porous material, so any sweat that is trapped under the belt will not evaporate. Your body releases the same amount of sweat it would release without the belt, but the belt will trick you into thinking you are sweating more than usual because the sweat in your core area will remain on your skin.
Saunas and steam rooms induce sweating and are associated with many health benefits.
Known as “sweat baths,” saunas have been used for health and wellness by several traditional cultures, including the Finns, the Turks, and some Native American communities. Saunas can be “wet,” meaning that high heat is combined with water to produce steam; “dry,” meaning that the heat comes from a wood-burning furnace; or both wet and dry, meaning that the room is heated by a wood furnace and water can be poured over hot stones to produce steam.
Spending a short amount of time – usually 15-20 minutes – in a sauna is a healthy practice that can ease discomfort from arthritis and asthma, rid the body of excess sodium, cleanse the skin, and ease strain on the liver and kidneys. However, saunas do not lead to weight loss.
While exposure to heat in a sauna can raise the heart rate and speed up the metabolism, the body does not burn enough calories while seated in a sauna for true weight loss to occur. Physically, the sweating that takes place in a sauna is no different from sweating under other circumstances. In all cases, sweating will result in short-term loss of water, which may register as weight loss on a scale. However, the body will return to its original weight once it has rehydrated.
Ultimately, there is only one way to achieve meaningful weight loss: burning more calories than we take in.
The common use of the word “burning” may make some people think that heat (and the sweating associated with it) leads to weight loss. This is a myth, however.
Skiing, snowshoeing, and open-water swimming are all activities that burn lots of calories in a cold environment. While sweating is a natural, healthy process that benefits the body, we do not need to artificially increase our body’s release of sweat. If losing weight is your goal, your best bet is to eat a balanced, healthy diet while also engaging in moderate exercise.