• Low testosterone has become normal these days, but it’s far from inevitable.
• Some men may need testosterone replacement therapy, but the vast majority can maintain healthy testosterone levels well into old age through a combination of a healthy diet, sufficient sleep, and a low-stress, fitness-oriented lifestyle.

Men these days aren’t what they used to be. And I mean that literally. The average testosterone level of American men has declined by roughly 1 percent per year since at least the mid-1980s, if not longer—that’s more than a 25 percent decline in 30 years. Nor is this strictly an American phenomenon; similar results have been reported in the UK and Denmark.

Contrary to popular belief, declining testosterone levels are not a natural and inevitable part of the aging process—one Australian study found that men who took care of their health typically did not experience a significant annual decline in testosterone levels.

Low testosterone is becoming the norm, and more men than ever are going on testosterone replacement therapy. However, there are ways to treat low testosterone naturally. Here’s how you can find out if you have low testosterone, and what to do if you have it.

How to Identify Low Testosterone

Low testosterone has a lot of potential symptoms. Watch for the following:

• Low libido
• Erectile dysfunction
• Depression
• Apathy
• Loss of muscle mass
• Fatigue
• Increased body fat levels
• Insomnia, or non-refreshing sleep
• Difficulty focusing

Any or all of those could be signs that you suffer from low testosterone—but they could also be caused by a number of other conditions. If you suffer from three or more of the listed symptoms, there’s a strong chance that your testosterone levels are low, but the only way to be sure is to get blood tests.

Go see your doctor, tell them about your symptoms, and tell them that you suspect you have low testosterone and would like to get tested. Insurance should readily cover this, but you’ll need to make sure you get the right tests. Most doctors don’t know very much about testosterone, and will only want to test for total testosterone. To get the full picture of your hormonal health, you’ll want to ask your doctor for all of the following:

• Total testosterone
• Free testosterone
• Sex hormone–binding globulin (SHBG)
• Luteinizing hormone
• Estradiol (the main form of estrogen)
• Thyroid-stimulating hormone

These tests will give you a clear picture of your hormonal health, but in and of themselves they probably won’t tell you why your testosterone is low. To figure that out, you’ll need to take a look at your diet and lifestyle.

How to Eat for High Testosterone

First and foremost, you need to eat plenty of fat, as well as some cholesterol. Your body uses fat and cholesterol to produce steroid hormones such as testosterone, estrogen, and cortisol. Accordingly, fat intake is positively correlated with levels of testosterone and most other anabolic hormones. A good guideline is to consume at least 75 grams of fat per day, or one gram per kilogram of bodyweight, along with half a gram of cholesterol.

If fat is good for you, popular diet science would have you believe that carbohydrates must be bad. The research doesn’t bear that out, however. While some people certainly get better results from low-carb or even ketogenic diets, studies have generally found that most men have higher testosterone levels when they don’t avoid carbs. Athletes also tend to do better on high-carb diets, as the carbs keep their muscles fueled for high levels of activity.

Surprisingly, those same studies have found that excessive protein lowers testosterone levels. While most people don’t eat enough protein, people who are really into fitness—particularly weightlifters—often have the opposite problem. For athletes, a good guidelines for protein intake is around 1.2–2 grams per kilogram of bodyweight, or 0.6–1 grams per pound of bodyweight.

And then of course there are vegetables. This part is simple: eat a lot of them. You should be eating at least five servings of vegetables and two servings of fruit a day, and you don’t need to worry about eating “too many” vegetables.

As for micronutrients, make sure to get plenty of iron, zinc, magnesium, and vitamin D. The first three can be had by eating meat, nuts, seeds, and leafy greens. Vitamin D is different—you’ll need to either get a half hour of sun every day, or take a daily supplement.

Live a Testosterone-Friendly Lifestyle

After your diet, the most important factor in your testosterone level is how well you’re sleeping. For maximal testosterone production as well as optimal health, you need to be sleeping seven to nine hours a night, in a dark room, on a regular schedule every night.

De-stressing is also an important part of a testosterone-friendly lifestyle. Stress reduces testosterone because cortisol, your body’s main stress hormone, is made from the same chemical precursor (cholesterol) as testosterone, so the two hormones compete with each other for raw materials. Stress can also directly cause some of the symptoms associated with low testosterone, like insomnia and loss of libido.

Finally, don’t smoke, and keep drinking to a minimum. Alcohol and nicotine reduce testosterone levels both directly, and indirectly by lowering sleep quality. Limit alcohol to one or two drinks, once or twice a week.

Lift Weights

While moderate amounts of cardio are good for your testosterone levels, doing a lot of cardio without ever touching a weight will lower your testosterone levels. Thankfully, lifting weights—with or without cardio—has been shown to raise testosterone levels.

No particular “style” of weightlifting seems to be better than any other here; the main consideration is volume, on a per-muscle level. Novice trainees should train each muscle group twice a week, intermediate trainees three or four times a week, and advanced trainees should train each muscle group at least five days a week.