One of the big culprits, for both men and women, is obesity. As a person's weight soars, their libido plummets, due to biochemical changes that diminish blood flow. Extra weight also hinders their ability to have children "with men, it's damaged sperm; with women, it's ovulation problems. (Manage your weight with more than just food intake.

FOR THE HORMONE RUSH
Eat This!
1-OZ DARK CHOCOLATE
162 calories
11 g fat (6 g saturated)
10 g sugars

Chocolate is full of anandamide and phenylethylamine, two compounds that cause the body to release the same feel-good endorphins triggered by sex and physical exertion. Cocoa also contains methylxanthines, which make skin sensitive to every touch. Aim for dark chocolate, which packs more cocoa than lighter milk chocolates, and keep portions small.

Not That!
WHITE CHOCOLATE

White chocolate isn't technically chocolate, since it doesn't contain any actual cocoa "which means no heightened skin sensitivity, or rush of the feel-good hormone serotonin.

FOR ENERGY
Eat This!
6-OZ SIRLOIN STEAK
414 calories
24 g fat (10 g saturated)
46 g protein

Protein has been shown to naturally boost levels of dopamine and norepinephrine, two chemicals in the brain that heighten sensitivity during sex. Your steak is also packed with zinc"a mineral that boosts libido by reducing production of a hormone called prolactin, which may interfere with arousal.

Not That!
AN ENERGY DRINK

While the caffeine and sky-high sugar content will initially leave you bursting with energy, you're setting yourself up for a major crash not far down the line. Additionally, Canadian scientists found that maintaining a diet high in sugar can temporarily lower your testosterone levels, which in turn can sap your sex drive whether you're a man or a woman. See, the more testosterone you have, the higher your arousal levels. Too much sugar sends your T into hibernation and your libido along with it.

FOR POWER
Eat This!
Ã,½ CUP VANILLA ICE CREAM
137 calories
7 g fat (4 g saturated)
14 g sugars
2 g protein

Ice cream has high levels of calcium and phosphorus, two minerals that build your muscles' energy reserves and boost your libido. All that calcium"200 milligrams in the typical bowl "can also make you more sexually charged, since the muscles that control sexual response need calcium in order to contract properly.

Not That!
TOMATOES

They're great for you in other ways, but tomatoes' lycopene and phytofluene can decrease testosterone levels. The effect isn't dramatic, but you may be better off skipping the marinara sauce if you want to get saucy.

FOR PERFORMANCE
Eat This!
1/2CUP BLUEBERRIES
40 calories
10 g carbs
7 g sugars

Forget Viagra. Mother Nature's original blue potency capsules may do even more for you. Blueberries are high in soluble fiber, which helps remove excess cholesterol from the blood before it gets absorbed and deposited on artery walls. Blueberries also relax blood vessels and improve blood flow. For maximum potency and performance, eat a serving of blueberries at least three or four times a week.

Not That!
SODA

Soda pop will sap your sex drive. Too much sugar will lead to spikes and crashes in your blood glucose, ultimately sapping your testosterone levels (and your libido).