Even if you can easily complete the daily crossword puzzle and regularly trounce your pals in Words With Friends—classic ways to keep your mind sharp—there may be other everyday habits chipping away at your intellect, sabotaging your precious neurons in surprising ways. Here are 6 things that top experts say could be harming your true brainpower.

1. You’re stressed out

Fretting about finances, worrying over work projects, and trying to maintain a semblance of a social life can create a potent stew of stress hormones. “High stress levels are not only associated with poorer brain functioning but may even link to an increased risk of Alzheimer’s disease,” says Brendan Kelley, MD, neurologist at The Ohio State University Wexner Medical Center in Columbus, Ohio. Hormonal changes linked to stress are believed to be behind this.

2. You can’t fit into your jeans

As if you need more incentive to stay slim, research shows mid-life obesity can result in poorer cognitive performance and an increased risk of dementia later on, says Kelley. A study published in the American Journal of Epidemiology shows a link between obesity and low intellectual ability in adolescence and adulthood. “Obesity is a complex medical problem, however,” says Kelley. It’s not easy to disentangle whether this is because of some of the medical issues that may result from obesity or from obesity itself, he says.

3. You’re living the sweet life

Sugar not only adds inches to your waistline, but in high doses, it could affect your brain cells, says Allen Towfigh, MD, a sleep medicine doctor and neurologist affiliated with Weill Cornell Medical Center/New York Presbyterian Hospital. “Diabetics have higher incidences of dementia,” notes Towfigh. The negative impact of sugar on the brain may be because of increased inflammation, according to an animal study from the University of Southern California. High sugar diets were found to affect brain cell functioning and cognitive ability.

4. You’re the master multi-tasker

Composing an email while having a discussion with your co-worker and eating lunch at the same time—sound familiar? This kind of juggling act can jam up your brain processing, says Towfigh. “Our frontal lobes are the main engines directing our attention, and they only have a finite amount of processing power.” If you try to exceed what your brain can reasonably do, your mind may stall out from time to time, similar to how your computer freezes up when you try to open multiple programs.

5. You spend time with a friend who smokes

Even if you don’t light up, inhaling second-hand cigarette smoke subjects the brain to a cocktail of toxic substances, says Towfigh. “Prolonged exposure to smoke increases carbon monoxide in the body, which displaces vital oxygen our brains and bodies need.” Damage to blood vessels and neurons disrupt the ability of brain cells to communicate effectively and retain information properly.

6. You’re always up the air

Chronic jet lag from a busy travel schedule can affect learning and memory for up to a month after you’ve returned home, according to research from the University of California, Berkeley. Traveling through different time zones disrupts your body’s normal circadian rhythm, says Elizabeth Lombardo, PhD, a psychologist and author of Better than Perfect: 7 Strategies to Crush Your Inner Critic and Create a Life You Love. “In addition to problems with sleeping, eating, and hormone regulation (all of which can also influence memory and learning), it serves as a significant source of stress on your body.”