Trimethylglycine(TMG) or commonly known as betaine is a molecule that's becoming more and more popular in preworkouts. Naturally found in beet root, broccoli, and spinach, Betaine has a few different mechanisms by which it can help with health and performance. Firstly, it acts as a methyl donor(similar to SAMe) to help transform homocysteine(an indicator of used for cardiovascular risk) into the amino acid cysteine.

Betaine also acts as an osmolyte, meaning it helps bring water into your cells for hydration, cell swelling and maintaining cell structure. There have been several studies about betaine, starting with a 2010 study from UConn where it was shown to increase strength and power, and improve VO2 efficiently. It's most conclusive study to date was from 2013 study which used trained athletes(avg of 4.8 years lifting experience!). This 6 week study from Cholewa et al. Gave 23 subjects either 1.25g of betaine 2x a day or a placebo and tested its effects on muscle mass, fat loss, and training fatigue. The results are pretty significant: 3% drop in BF, 5.3lb gain in LBM, and 6.4 decrease in fat mass.

There is also evidence suggesting that it can have an build up effect, similar to how beta alanine works. Another study showed decrease fatigue and increased training volume, but only after 4 weeks of supplementation. The EFFECTIVE DOSE seems to be 2.5g a day, preworkout for improved workouts and gains in muscle mass. It's mechanism on fat loss is still unclear but it is believed to possible increase GH/IGF-1 release and increase protein synthesis, possibly from converting homocysteine into cysteine. Its definitely something worth looking into, especially if you're at a sticking point and want to train harder/longer.