Too much of a good thing can actually be very bad for your health—and it’s not always obvious which habits are dangerous. Here are five seemingly healthy habits which are good for you in moderation, but can cause serious harm when taken too far. Read on—and to ensure your health and the health of others, don’t miss these Sure Signs You’ve Already Had COVID.

Staying hydrated is obviously important for health, but with conflicting advice on the correct amount of water to drink, it’s easy to have too much—which can cause a dangerous condition called hyponatremia. “It can be lethal, but essentially all deaths from exercise-associated hyponatremia are 100 percent preventable,” says Dr. James Winger, a sports medicine physician at Loyola University Medical Center. “We are, however, seeing hyponatremia in new settings, such as American football, paddling and long distance ocean swimming. This is supported by the common but erroneous belief that mild-to-moderate dehydration during exercise is detrimental to health or performance.” So how much water should you drink?

“Drink only if you’re thirsty, and never feel as if you have to force yourself to drink more,” says Megan Schimpf, M.D. “A lot of foods contain water, which helps us meet this threshold, and few of us are in danger of becoming dehydrated. The body has a highly sophisticated regulatory system that monitors hydration and then sends you a message to drink when you need to.”6254a4d1642c605c54bf1cab17d50f1e

Exercise is a wonderful way to stay fit and manage stress—but working out too much or too hard can be detrimental to your health. “Anybody can be at risk for over-exercising, not just athletes,” says Caitlin Lewis, MD, sports medicine physician. “It means too much exercise in a short period, which is very common and can occur quickly. Sometimes overtraining happens to people who are just starting a program and do too much, too soon.”

According to Dr. Lewis, signs of overtraining may include:

• A profound feeling of fatigue.
• Energy loss.
• Chronic colds, infections and other illnesses.
• Insomnia.
• Weight gain.
• Stamina decline.
• For women, a loss of their period (amenorrhea).

Recovering from overtraining can take up to two months—when you do start working out again, ease into it gently. “I recommend that people work together with their physician, as well as a personal coach or trainer, to gradually return to exercise when safe,” says Dr. Lewis.

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The CDC recommends adults get at least seven hours of sleep every night for optimum health, but getting too much sleep—while not as common as chronic sleep deprivation—is linked to a number of health conditions including diabetes and heart disease. “Oversleeping can come with some unwanted—not to mention counterintuitive—side effects, including daytime sleepiness. But, if you’re only doing it here and there, getting more sleep than you need typically isn’t harmful to you,” says Dr. Aarthi Ram, neurologist specializing in sleep medicine at Houston Methodist. “In some cases, however, regularly oversleeping can be a sign of an underlying health condition…The exact amount of sleep that’s best for each person varies, but the average adult typically needs somewhere between seven to nine hours of sleep per night.” Dr. Ram also recommends ditching the snooze button: “The 10 more minutes of sleep you’re granting yourself over and over and over isn’t productive sleep. You’re not going to feel more rested by continuing to snooze your alarm clock. If anything, all of that interrupted sleep will make you feel more groggy.”

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Brushing your teeth twice a day is vital for good oral hygiene—but aggressive over-brushing is not only unnecessary, it can cause serious damage to gums and tooth enamel. “For most people brushing begins with a soft-bristled, multi-tufted toothbrush with fluoride toothpaste that helps strengthen enamel,” says Andrew Thompson, DDS, PC. “You should hold the brush at a slight angle and brush with a gentle motion to remove plaque, the main cause of gum disease and tooth decay—if you’re too aggressive by brushing too hard or too long, you could damage the gums. You should brush no more than twice a day for two minutes, and at least thirty minutes to an hour after eating to allow saliva time to neutralize any remaining acid and help restore minerals to enamel.”

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There is a point where obsessing over health—specifically over diets and “clean” eating—becomes dangerous, and increasingly restrictive eating becomes normalized. “Orthorexia is defined as an unhealthy obsession with healthy food,” says Dr. Steven Bratman, who coined the term in 1997. “It’s not the diet that is orthorexia, it’s the diet that could lead to it. The more extreme or restrictive the diet, the more likely it could lead to orthorexia.”

“I have absolutely seen a rise in orthorexic patients as a nutrition therapist. It’s almost rising exponentially. Now I get a new client every week with orthorexic symptoms. It is a serious problem,” says nutritional therapist Dr. Karin Kratina. “There is nothing wrong with eating local or being a vegetarian or vegan. I think a lot of those diets are inherently valuable. The problem is that we have moralized eating, weight, food, and exercise. Food has become presented—more and more—as the answer.” Worried about your diet? Talk to your health provider and come up with a healthy eating plan that’s best for you. And to protect your life and the lives of others, don’t visit any of these 35 Places You’re Most Likely to Catch COVID.