Does caffeine reduce the effects of weight lifting on mass gaining by activating metabolism, either for every individual or more specifically for ectomorphs who already have fast fat burning mechanisms ?
Metabolic effects of caffeine may vary depending on whether one is 'naive' to caffeine (infrequent user) or 'accustomed' to caffeine (daily user). Metabolic effects may also vary due to genetics, specifically a polymorphism on the CYP1A1/2 enzyme (1)
One review notes that, after looking at the differences in metabolism between humans and rats, that a 10mg/kg bodyweight dose in rats is roughly bioequivalent to 250mg in a 70kg person. (2)
Dose Response Effects Of A Caffeine-containing Energy Drink On Muscle Performance: A Repeated Measures Design
Change of Effect: None
Trial Design: Double blind
Trial Length: 24 hours
Number of Subjects: 12
Gender Both Genders
Ages: 18-29, 30-44
Body-Types: Trained, Average
Notes for this study:
In 12 active and healthy participants (light caffeine consumers at less than 60mg daily), an intake of a caffeinated energy drink (compared to placebo, the same energy drink but not caffeinated) was able to increased blood pressure and heart rate at rest without significantly affecting metabolic rate up to 3mg/kg bodyweight.
Power output, as measured by half-squat and bench, was increased only at 3mg/kg bodyweight with no significant influence at 1mg/kg.
Caffeine: A Double-blind, Placebo-controlled Study Of Its Thermogenic, Metabolic, And Cardiovascular Effects In Healthy Volunteers
Change of Effect: Increase
Trial Design: Double blind Trial Length: 24 hours Number of Subjects: 6 Gender: Both Genders Ages: 18-29, 30-44 Body-Types: Untrained, Overweight, Average
Notes for this study:
In low habitual coffee drinkers (150-300mL daily), supplementation of 100-400mg caffeine increased the metabolic rate (9.2+?-5.7, 7.2+/-6.0, and 32.4+/-8.2kcal/h increase) with the highest dose also increasing plasma glycerol (indicative of fat burning) and lactate. Blood pressure was increased at 400mg only in supine position.
Footnote: Somatotypes aren't real. They are the result of a now debunked theory of psychology and had nothing to do with predicting how one gained fat or muscle. Describing yourself by one of the three somatotypes is just a limiting belief and a rationalization for failure.