Tip: It Grows Muscle, Too

The researchers procured 30 mice and strictly regulated their environment. They got 12 hours of daylight and 12 hours of darkness. The temperature stayed the same. The activities of the mice were restricted to playing craps or reading the mouse aspirational novel, "Flowers for Algernon."

More importantly, they were given unrestricted access to food and water. One group ate a normal, unsullied diet. The second group ate essentially the same diet, only it was supplemented with 0.3% coffee. The third group's food was supplemented with 1% coffee. The animals stayed on the diet for 7 weeks and were weighed weekly.

Coffee, in a dose-dependent manner (the bigger dose had bigger results), increased gastrocnemius muscle weight and muscle fiber size. Likewise, the weights of the quadriceps, tibialis anterior, and extensor digitorum longus all increased in weight (but not fiber size).

Perhaps curiously, the coffee for some reason had no effect on triceps and soleus muscles. The 1% dose, unlike the 0.3% dose, had the additional benefit of increasing grip strength in the mice. As far as fat levels, the coffee didn't alter levels of subcutaneous fat or epididymal (fat around the heart and organs).

In short, coffee increased muscle function and skeletal muscle hypertrophy in the mice. The researchers noted several causes, all at the biochemical level. The coffee elevated the expression of PGC-1-alpha, which improves muscle function and decreases fatigue.

Other contributing factors included suppression of myostatin (the less myostatin expressed, the more muscular growth) and an uptick of IGF1, a premier muscle growth factor.

If you convert the dosage of coffee (note that it's coffee, not caffeine) used in the experiment from mice to humans, you get 27 mg/kg for the low dose and 81 mg/kg for the high dose. For a 200-pound man, that translates to about 2 cups a day (for the low dose) to about 4 and a half cups a day (for the higher dose).

Let's look at this realistically, though. You're not likely to develop any noticeable or appreciable amounts of muscle if you suddenly up your coffee intake from 2 cups a day to 4 or more.

I suppose it's possible, though, based on this experiment, to maybe experience some slight benefit to muscle size and strength if you're coffee naive, i.e., if you're not being exposed on a regular basis to coffee or the coffee polyphenols chlorogenic acid and caffeic acid (or any other polyphenols that might play a role in this phenomenon).

However, the takeaway from this study should probably be that there are plenty of good reasons to drink coffee every day and this is just another one. That, and cholorogenic and caffeic acid might be worthy of consideration as standalone supplements.

1. Jang YJ et al. Coffee consumption promotes skeletal muscle hypertrophy and myoblast differentiation. Food Funct. 2018 Feb 21;9(2):1102-1111. PubMed.