Metabolic ThyroLean: ProLab's Natural Thyroid Booster! -

Metabolic ThyroLean: ProLab’s Natural Thyroid Booster!

Prolab’s Metabolic Thyrolean is a NON-stimulant, ephedra-free fat burner. There are no ephedrine or caffeine-related compounds in this formula so it’s not for you if you are expecting to get a a boost of energy from your fat burner. On the other hand, it’s an ideal product to investigate if you’re sensitive to stimulants.

Ingredients include calcium, various phosphates, potassium, phosphatidylcholine, l-tyrosine, hydroxycitric acid and Gum Guggul extract. Let’s have a closer look at the formula and evaluate it for potency…

1. Phosphates & potassium: Often included in fitness supplements (generally to maintain a proper electrolyte balance and to improve athletic performance). In this case, it’s obviously to improve the effectiveness of Thyrolean — one study indicates…

“Phosphate supplementation prevents a decrease of triiodothyronine and increases resting metabolic rate during low energy diet.” (see J Physiol Pharmacol. 1996 Jun;47(2):373-83)

Another study concluded…

“… the present study confirmed a potential usefulness of phosphate supplementation during energy restriction in obese patients due to its effect on resting metabolic rate.” (see J Physiol Pharmacol. 1993 Dec;44(4):425-40).

Two other studies also showed promising results (see Miner Electrolyte Metab. 1994;20(3):147-52,Int J Obes. 1991 Jun;15(6):429-36).

Given that Metabolic Thyrolean is a “thyroid” boosting product, it makes sense that these ingredients are included.

2. Phosphatidylcholine: this is a phospholipid derived from lecithin, and a component of cell membranes. It’s a good source of choline, which is used by the body to synthesize acetylcholine, a neurotransmitter (click here for the full review).

3. Gum Guggul Extract (2.5% Guggulsterones): Gum Guggul is actually a resin produced by a tree native to India. The standardized extract called “guggulipid” or “guggulsterones.” Used in India for 100’s of years by those who practice natural medicine, there does seem to be some indication that gum guggul may play a role for those interested in weight loss, as well as maintaining a healthy cholesterol profile. For instance…

Several studies have validated guggulsterones’ ability to lower cholesterol levels (see J Assoc Physicians India. 1989 May; 37(5):323-8). On the other hand, a later study published in The Journal Of The American Medical Association contradicted previous studies demonstrating guggul’s LDL-lowering effects.

A small body of evidence also indicates guggulsterones may also have value as a fat burner (see J Postgrad Med. 1995 Jan-Mar;41(1):5-7) specifically by increasing thyroid T3 hormone levels. How it does this is a matter of some speculation.

Nonetheless, an increase in thyroid hormone levels will boost the metabolic rate. Caloric restriction, of course, causes a decrease in the metabolic rate. Keeping the metabolism chugging along happily despite a restriction in calories is about as close to the dieter’s holy grail as you can get.

Unfortunately, Thyrolean’s guggul dosage is a little on the low side — it delivers slightly less than 19 mg of active guggulsterones per serving. Anyone really looking to investigate with guggul’s thyroid-boosting power might be better of with Syntrax’s Guggulbolic Extreme.

4. Garcinia cambogia Extract: Standardized for hydroxycitric acid… an ingredient that has been pretty much debunked for weight loss. You can read the full review of all the details!

5. L-tyrosine: Because l-tyrosine, an amino acid, is a precursor to the thyroid hormone thyroxine (also known as T4) supplementation may have a positive effect on thyroid hormone levels which may contribute to an increased metabolic rate. Unfortunately, clinical data validating l-tyrosine’s thyroid-and-metabolism boosting characteristics is in darn short supply (see the full l-tyrosine review here!)

Bottom line?

Although Thyrolean could definitely do with a little stronger dose of guggulsterones, this isn’t a bad formulation. But what really sets this product aside for other similar ones it its price — it retails for under $20. (Thyrin ATC, for instance, retails for between $32-$72 online, while another product, Thromine, sells for around $40. Thyrotril, from Sterling Grant Labs, sells for about $40).

While I’ve never heard of anyone obtaining fantastic results with these products, they might help keep thyroid levels elevated during periods of extreme dieting (which should be short, due to the loss of muscle mass such diets usually promote). And while I would be hesitant to spend $30 or $40 on such a product, I’d probably spend $20 just to give it a try.

Your call.

Author: Paul

Paul Crane is the founder of His passions include supplements, working out, motorcycles, guitars... and of course, his German Shepherd dogs.


  1. Do any of these work if you don’t have a thyroid but are taking thyroid medicine?

    Post a Reply
    • Margie, I wouldn’t touch any fat burner in your case unless you get an OK from your doctor. Most of these products are not recommended for anyone with thyroid issues.

      Post a Reply

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