Phase 2® Carb Blocker And Starch Neutralizer Review
Phase 2® is the name for the proprietary, clinically studied version of white kidney bean extract. White kidney bean extract is a common ingredient in many fat burners, although only a few contain the registered Phase 2 version (you may also see white kidney bean extract referred to as Phaseolamin, or Phaseolus vulgaris).
Of course, the question is…
Why is white kidney bean extract common in so many fat burners and carb blocker products?
Mostly, it’s because white kidney bean extract is thought to interfere with the action of the enzyme amylase, which is required for the proper digestion of carbohydrates. In theory, Phase 2® prevents amylase from converting carbohydrates into sugar, thus effectively “blocking” a portion of those carbohydrate calories from inevitably being converted into fat and being deposited on your waistline.
Unfortunately, the scientific data indicating this is so isn’t overwhelming. A 2004 UCLA study on Phase 2® concluded…
“Clinical trends were identified for weight loss, inches lost from the waist, energy, and decrease in triglycerides, although statistical significance was not reached. The reason that significance was not achieved was the small number of subjects who completed the study and the wide variability of the results within each group. Further studies with larger numbers of subjects are necessary in order to definitively demonstrate effectiveness.”
So while things certainly look promising for white kidney bean extract, it would certainly be incorrect to call it a hands-down winner (incidentally, white kidney bean may have other weight-loss benefits — it may improve lipid profiles in obese individuals — Nutrition 2002;18:729-33, and may help to lower the GI (glycemic index) levels of high GI foods).
I’ve also had the opportunity to chat with a couple of people who used white kidney bean based carb blockers and actually gained weight. To be fair, I suspect that this had more to do with the overeating of simple carbohydrates, brought on by the false sense of security afforded by the use of a carb blocker.
To their credit, the makers of Phase 2 (Pharmachem), don’t encourage users to go hog-wild. Several years ago, the company was given clearance by the FDA to make the following “structure-function” health claim:
“May assist in weight control when used in conjunction with a sensible diet and exercise program.”
The importance of the “sensible diet and exercise program” bit can’t be over-emphasized. While Phase 2 may well inhibit starch digestion in the stomach and small intestine, it…
1. …won’t prevent the digestion of all carbs – sugar digestion/absorption, for example won’t be inhibited. If rice, bagels or mashed potatoes are on the menu, great. On the other hand, chocolate chip cookies, doughnuts and apple pie a la mode are problematic, thanks to their sugar and fat calories.
2. …won’t prevent starch fermentation – and the production of absorbable short chain fatty acids – in the large intestine by colon bacteria. As noted in this review on Phase 2:
“It increased the post prandial delivery of carbohydrates to the distal small bowel by 22 to 24% (as measured by oroileal tube aspiration) and increased hydrogen concentrations in the breath from 30 to 90 minutes after the meal. Hydrogen breath testing is an accepted method of determining carbohydrate malabsorption as colonic bacteria ferment carbohydrates into organic acids, carbon dioxide and hydrogen.”
Obviously, some additional fermentation occurs when Phase 2 is consumed with a starch-containing meal. Thus, some of those “undigested” starch calories may end up getting reabsorbed for use as energy.
Ultimately, the true number of unabsorbed starch calories can only be discovered by measuring fecal excretion – something that has yet to be done case of Phase 2. Until such measurements are made, it would be foolish to assume that Phase 2 can limit the absorption of all – or even most – starch calories. Thus it’s not “written permission” to over-indulge in high-carb foods, except (perhaps) within the context of the occasional “cheat meal.”
If you’re interested in experimenting with Phase 2, you’re in luck: it’s not very expensive when purchased as a standalone supplement. For example, iHerb – one of our recommended retailers – sells 180 500mg caps of Phase 2 for $18.48 (use the coupon code FAT259 to get $5 off your first order).