Even the smartest, most health-conscious people can make bad choices when it comes to their health and fitness. Here are a few mistakes to watch out for:

  • Trying to lose weight by drinking diet soda. A University of Texas study found that people who drank one diet soda a day for 7 years were 41% more likely to be overweight than non-soda drinkers. The reason? Diet drinkers often eat more because they believe their beverage of choice is “saving” them calories. And studies show that artificial sweeteners increase our appetite for sugary foods.

  • Popping “extra” acetaminophen – the active ingredient in Tylenol – thinking that if some is good, more has to be better. Organ transplant specialist Dr. Anne Larson says that exceeding the adult dose of 650 milligrams every 6 hours – that’s 2 regular strength tablets – can permanently damage your liver. And don’t mix Tylenol with other drugstore remedies. Nearly all over-the-counter meds for cold, flu, allergies, and sinus also contain acetaminophen. And so do most prescription painkillers like Vicodin, which means it’s easy to take a toxic overdose.

  • Skipping a second opinion. In a recent survey of almost 7,000 doctors, half of them said they discover a wrong, late, or completely missed diagnosis at least once a month. That means, statistically speaking, your doctor is highly likely to miss something. Most of them are minor things that don’t really harm the patient. But if your doctor recommends surgery or any serious procedure, you should consult with at least one more physician before you sign the consent form.

  • Getting tipsy. 2-out-of-3 people make this mistake. Research shows that drinking until you’re intoxicated one weekend a month triples your risk of heart disease. That’s especially true for women, because they have lower levels of the stomach enzymes that metabolize alcohol, so they’re more likely to experience alcohol toxicity than men.