Testosterone, natural. In 2007 I took anabolic steroids. A doctor prescribed them. This helped me. But synthetic testosterone is not ideal. Natural is best.
To increase testosterone, science has insight. Lifestyles—the things we eat, our exercises, our body fat—influence circulating testosterone. We can increase T naturally.
Important. A man's testosterone level is important. It determines his health, his body composition, his sexual drive. Many common diseases and lifestyle choices reduce it.
Increase T without medication:

Lift weights
Drink water
Eat saturated fat
Lose fat
Avoid hot baths
Avoid endurance activities
Avoid cold temperatures
Garlic. It gives you toxic breath. But one way to increase testosterone is to eat garlic. This is one reason why garlic is available in supplement form. It increases T levels.

Details:In a study, rats fed more garlic had more testosterone. These rats would end up posing for rat bodybuilder magazines.

Garlic: Testosterone

These results suggest that dietary supplementation with... garlic alters hormones associated with protein anabolism by increasing testicular testosterone and decreasing plasma corticosterone in rats fed a high protein diet.

Garlic supplementation increases testicular testosterone
Fenugreek. This is a supplement. It helps with arthritis and with women's issues. But it also has been shown to bring T levels in men up to normal levels.

Tip:Fenugreek seed extract is available in supplement food at health food stores or online. It is inexpensive as well.

Fenugreek: Testosterone

It was concluded that Testofen [fenugreek extract] demonstrated a significant positive effect on physiological aspects of libido and may assist to maintain normal healthy testosterone levels.

Physiological Aspects of Male Libido
Aspirin. This has been shown to reduce cortisol levels and increase testosterone levels. It does this over a period of 8 to 10 days. And this may promote better bodybuilding results.

Thus:Aspirin has many benefits for heart health. But it may also help increase your testosterone levels. It is safe and cheap.

Aspirin, Bodybuilding
Tea, green and black. This is perhaps the best natural supplement. New research (2012) shows that green tea acts in a way similar to anabolic steroids.Tea: Testosterone

Note:Tea is the only food that does this. It inhibits a process called testosterone glucuronidation.

Info:This process breaks down testosterone in the body. When green tea inhibits this process, circulating testosterone levels raise.

Performance-enhancing:This means green tea leads to higher testosterone. Green tea is a performance-enhancing drug.

The anabolic steroid testosterone can be used by athletes to enhance athletic performance and muscle growth.... Inhibitors of testosterone glucuronidation could have an impact on circulating testosterone levels, thus aiding performance, as well as... masking testosterone abuse.

Dietary green and white teas
Green tea is studied a lot in research. It leads to less body fat and more muscle mass. It may lead to increased T and better athletic performance.

Tip:Drink several cups of green tea each day. Even drinking a gallon of green tea every day would be beneficial.

Important:It would lead to less fat and more muscle mass—even with no exercise. Do you like the couch?

Black tea:This has less performance-enhancing chemicals in it (called catechins). But it also helps (go easy on the sugar).

Coffee. This is another way a man can increase his T levels. One study showed that men who consumed caffeine, in the form of chewing gum, has higher testosterone levels.

Caffeine:Coffee, with caffeine, would also lead to higher testosterone levels.

Coffee: Testosterone

Following caffeine treatment, testosterone increased... relative to the placebo condition.

Caffeinated chewing gum: study
Coffee versus tea. From my research, the health benefits of green tea are more established and greater than the health benefits of coffee. Green tea is better than black tea and coffee.

Tip:If I were choosing a drink to improve my health, I would use high-quality green tea. Coffee and black tea are also effective.

Lift weights. This is one way you can naturally increase testosterone. Many studies have measured the testosterone levels of men before, during and after lifting.

Important:Lifting does not simply increase testosterone. Instead, it modifies the ratio of hormones in your body.

Ratio:Cortisol is part of the testosterone-cortisol ratio. Lifting weights modifies this ratio so that more muscle growth occurs.

Lift Weights: Testosterone
Testosterone, cortisol. The testosterone-cortisol ratio is important. Lifting weights modifies this to have more benefits. The science (as always) is complex.

Previous studies with different results have suggested that total and bioavailable testosterone levels are modified by physical exercise. Such changes may be related to modifications in cortisol levels and could be reflected in some urine androgens.

SHBG, plasma and urinary androgens in weight lifters
Full-body exercises, such as squats and deadlifts, are best for influencing the testosterone-cortisol ratio. This leads to most muscle mass growth.

Growth hormone:Weight lifting also modifies the level of growth hormone available. This requires enough sleep to be effective.

Growth Hormone

Sleep:For increasing growth hormone levels, the second half of the night's sleep is important.

Water. Does water affect testosterone levels? As a bodybuilder, you want high T levels. This increases muscle mass. Drinking enough water is considered important for fat loss.

So:I investigated this using PubMed. I found a scientific study done on college runners.

Water, study. The study measured the levels of the men's testosterone and cortisol levels. The measurements were taken at various times.

Measurements:Some were done in a dehydrated state (hypohydration). Others were done in a normal health state (euhydration).

Hydration state had no measurable effect on testosterone concentrations before, during, or after exercise at either intensity. Regardless of exercise intensity, cortisol concentrations were greater during hypohydration than euhydration pre-exercise and 20 min post-exercise.

Hydration state: testosterone and cortisol
Water, continued. Testosterone was not directly affected by how much water the men drank. Instead the cortisol level was much greater when the men did not drink enough.

And:Cortisol breaks down tissue. Testosterone helps build it. This is a simplification. The actual biology is (as usual) complicated.

Tip:The testosterone-to-cortisol ratio is improved when you stay hydrated. This is key to bodybuilding.

Saturated fat. Eating saturated fat leads to higher testosterone levels. Foods like butter, coconut oil and canola oil contain lots of saturated fat.

Study:One study tested the effects of these oils on rats. The rats given coconut oil had the highest increase in testosterone levels.

But:Other foods containing saturated fats, like butter, canola oil and other oils, also would be effective.

Butter: Testosterone

In addition, levels of Testosterone in the [canola oil-fed rats] and [coconut-oil fed rats], and Free Testosterone in the [coconut-oil fed rats] had a remarkable increase.

Effect of consumption of fatty acids
Butter tip. A small amount of butter could be added to every meal. The main point is that eliminating all fat from the diet is not a good way to maintain high testosterone levels.

Warning:A low-fat diet decreases T and growth hormone. This does not end up with you on the cover of a muscle magazine.

Eggs:Another good food for getting more saturated fat is eggs. These can contribute to higher testosterone.

Lose fat. Obesity is harmful to health. This is common knowledge. There is an inverse correlation between testosterone and obesity.

Thus:With more obesity, testosterone is lower. If an overweight man loses fat, his T levels may increase.

Several studies have confirmed the significant inverse correlation between testosterone and obesity.... After decades of intense controversy, a consensus has emerged that androgens are important regulators of fat mass and distribution.

Impact of testosterone on body fat composition
Sleep. Make sure to get enough sleep. Science has found that when people are in "sleep debt" and are sleep-deprived, testosterone decreases.

And:Cortisol increases. This leads to muscle atrophy—smaller, weaker muscles.

Sleep is important for maintenance of skeletal muscle health. Sleep debt can induce muscle atrophy by increasing glucocorticoids and decreasing testosterone, growth hormone and insulin-like growth factor-I.

Resistance exercise: A non-pharmacological strategy
Improve sleep. Because sleep is so important, you must ensure you do nothing to cause your sleep quality to decrease. Avoid caffeine before bedtime.

Also:Exercise most days to be tired enough to sleep at night. Often the easiest way to get more sleep is to go to bed earlier.

Hot baths. Research has shown that old rats have reduced testosterone levels after being placed in hot baths. Humans are likely affected in the same way.

So:It is a good idea to avoid exposing your balls to excess heat. Generally be careful with your balls. They are important.

And:Wearing loose, cooler underwear and not taking excessive hot baths will possibly help increase your T levels.

Hyperthermia significantly decreased the testicular testosterone level in old male rats.... These data imply that frequent hot baths might impair testicular steroidogenesis, especially in old men.

Testicular steroidogenesis, hyperthermia
Avoid endurance exercise. In an ultra-endurance race, athletes run or ride long distances. Their testosterone levels decrease (are suppressed) from this activity.

Tip:Shorter bursts of exercise, like lifting a heavy barbell, are better than sustained activities like marathons.

Severe physical and environmental stress seems to have a suppressive effect on the hypothalamic-pituitary-gonadal (HPG) axis in men....

Hormonal responses, race across frozen Alaska
Avoid cold weather exertion. Long-term exertion in freezing weather will reduce testosterone levels. To maintain good T levels, avoid exertion in freezing temperatures.

Seven men completed an 850-km North Pole expedition in temperatures varying from -3 degrees C to -47 degrees C.... Declines in cortisol, total testosterone, bioavailable testosterone and free thyroxin returned to normal values....

Hematological profiles, North Pole expedition
Masturbation. Scientists have found that men's testosterone levels increase when aroused. Movies or images even increase T. Masturbation is thus beneficial to T levels.Masturbation

Note:Most healthy men already masturbate. So this tip is not likely to improve your testosterone.

A story. Years ago I had low testosterone. An endocrinologist I visited found my level was low and prescribed me a lot of steroids (Depo-Testosterone, Androgel).Androgel
In retrospect, I think these steroids were too much for me. My testicles shrank in size. I became more athletic and had more interest in exercise.Testicles, Shrinkage

However:I think natural ways to increase testosterone, like those I shared, are a better approach.

And:If done in the long-term, I think they can fix mild cases of low-testosterone in men (not severe medical problems).

Bulk up. Some boys and men might want to increase their testosterone to gain huge muscle mass quickly. This is a normal and healthy desire. Eat more and lift heavy.Bulk Up
Low testosterone. This condition is called hypogonadism. It can be caused by bad testicles or a bad brain. I had issues relating to my head—so my balls are working correctly.Low Testosterone
Muscle magazine. I don't know if these tips will help you get on the cover of a muscle magazine. I never did. I am too fat. But improving your health is most important anyways.
Increase T. There are many ways to increase testosterone. This list is not comprehensive. But it offers some of the easier and more direct ways to boost your T level.
Medicine. If a medical condition exists, please consider medications. Trying these natural approaches is a first step for men hoping to improve health and quality of life.