ZMA is a nutritional supplement and works by providing the body with adequate levels of zinc, magnesium and vitamin B6. As the body does not store zinc, it must be replenished via diet. Magnesium is a macroelement (meaning the body requires relatively high levels of it) that is involved in over 300 different cellular processes. ZMA usually contains the recommended daily dose of magnesium and a larger dose of vitamin B6.

Research suggests that ZMA has a lot of different health benefits. A study performed at Western Washington University had football players take either the supplement or a placebo every night during an eight-week training program.

They reported that the athletes taking the ZMA experienced more than a 30 % increase in testosterone levels. The place placebo group had at the same time a 10 % decrease in testosterone levels and a greater than 20 % decrease in levels of IGF-1. In addition to the improvements in their anabolic hormone levels, the ZMA-supplemented athletes made significantly greater improvements in strength and power and also achieved better sleep quality than a placebo group. Better sleep quality also helps to aid in recovery.

A 2007 study from Selcuk University reported that four weeks of zinc supplementation in men increased testosterone levels at rest and after exercise. The same researchers also found similar results for zinc supplementation on testosterone levels in a prior study with competitive wrestlers.

Researchers from the USDA reported that zinc depletion decreased muscle endurance in subjects. This means that maintaining optimal zinc levels is critical for your ability to complete a number of reps with a given weight.

The same Western Washington University research team that did the ZMA research also discovered in an earlier study that when subjects supplemented with magnesium while following a 7-week leg training program, their leg strength increased by 20-percent more than those taking a placebo.

Both zinc and magnesium are also suggested to blunt cortisol, a catabolic hormone.

German researchers found that triathletes taking a magnesium supplement for four weeks maintained healthy cortisol levels at rest and after a triathlon, as compared to athletes taking a placebo. 

Brazilian researchers reported that subjects supplementing with zinc maintained healthy cortisol balance.

ZMA enhances sleep quality due to magnesium's ability to normalize and extend stage 3 and stage 4 slow-wave sleep. This is critical, as deeper sleep can help to raise GH levels, which peak during the night.

Zinc is also critical for maintaining thyroid hormone production. This is important for keeping your metabolic rate (the amount of calories you burn each day) and fat-burning capabilities up. Being low in zinc can limit thyroid hormone production, and compromised thyroid hormone function results in a lower metabolic rate, which makes it harder to drop body fat. Research confirms that when your diet is low in zinc, thyroid hormone levels fall and resting metabolic rate drops.

One study from the University of Massachusetts (Amherst) found that subjects placed on a low-zinc diet had significantly lowered metabolic rates. When the subjects took 25 mg of zinc each day for 20 days, their metabolic rate jumped up to levels that were higher than even before they followed the low-zinc diet.

The Selcuk University studies also showed that four weeks of zinc supplementation increased thyroid hormone levels in male wrestlers and sedentary men.

It appears that zinc is not only critical for thyroid function, but also for maintaining levels of the hormone leptin. This hormone is also important for keeping your metabolic rate high as well as keeping hunger down. Being deficient in zinc has been shown to significantly lower leptin levels.

It is well established that zinc is critical for immune function. Zinc affects multiple aspects of the immune system. Research from the Cleveland Clinic suggests that supplementing with zinc helps to support a strong immune system.