Mind the fat. Bears load up on fat before hibernating, but high-fat diets make humans “less functional and more sluggish.” Make sure that “only 25 percent to 30 percent” of calories come from fats—mostly “good” ones such as those found in olive oil, salmon, and avocados.

Put away protein. The amino acids in protein are “building blocks” of the immune system, forming “protective white blood cells and antibodies.” Eat up to 50 grams a day of lean protein sources such as fish, eggs, and skinless poultry.

Add color. To boost your immune system, eat fruits and vegetables in “vibrant shades”—red, orange, yellow, and green. Rich in antioxidants and carotenoids, they can “help immune cells surround and kill off a virus.”

Get moving. By dedicating just 45 minutes five times a week to moderate exercise, you can “cut down sick days by up to 50 percent.”

Source: Real Simple