The thyroid is a remarkably tough organ. Bodybuilders routinely subject it to a great deal of harsh treatment with the use of various drugs to lose fat, and it always seems to bounce back better than ever, and fairly quickly to boot. T3, T4, and Cytomel are all drugs which are commonly used to manipulate the function of the thyroid. This is very useful for getting into shape for a show. Synthroid has emerged as a viable option for thyroid management in the pre-contest phase in recent years. It is similar to Cytomel, the only difference being that as a synthetic version of T4, it doesn’t positively affect T3 levels (leading to weight loss) in the same way that T3 does.
It’s still a very useful drug for weight loss it just doesn’t work as efficiently on thyroid management.
Synthroid should not be used by bodybuilders who are currently using extremely low-carbohydrate, high protein Ketogenic diets. In cases like these, stick with Cytomel or the more traditional Clenbuterol or ECA (ephedrine, caffeine, aspirin) stack. Ketogenic diets are very popular these days, and the interactions with some drugs have yet to be studied to a large degree.
Bodybuilders should use up to 300 mcgs per day of Synthroid. This is much higher than the 100 mcgs daily they would run with Cytomel, but that is because Cytomel is just that much stronger of a compound. There isn’t a great deal of studies that have been done on dosing variances with Synthroid. The 300 mcgs number is the result of numerous discussions with athletes not clinical tests. It’s still a very “de facto”, not “de jure” drug.
Synthroid is more expensive than Cytomel. For this reason, most bodybuilders opt for Synthroid only when they discover Cytomel isn’t available. Additionally, since Cytomel has popular medical uses, it may be much more available, and may be more easily obtained without setting off any alarm bells at Customs. Additionally, there is a great deal of research on the effects of Cytomel on bodybuilders and fitness athletes leading up to a show. Most bodybuilding nutritionists (drug gurus) worth their salt can easily discuss the interactions and implications of using Cytomel. However the use of Synthroid is much less discussed and familiar.
All users should be aware that there is the potential for damage to the thyroid from use that is too heavy. Small use can take place for a long period of time with minimal chance of damage. The thyroid usually returns to full function in just a few weeks. However, very heavy use/abuse of these compounds can cause irreversible damage in a very short period of time. Take it easy when you use thyroid altering compounds. Check your BBT (basal body temperature) or have your thyroid function checked every 8 weeks as a part of a standard blood panel. It’s not an enjoyable part of the bodybuilding experience (having blood drawn), but it’s a very good way to get in front of small problems with body function early before they become larger issues.