Isagenix is a wellness system sold by multilevel marketing. It consists of a suite of products to be used in various combinations for “nutritional cleansing,” detoxification, and supplementation to aid in weight loss, improve energy and performance, and support healthy aging. It allegedly burns fat while supporting lean muscle, maintains healthy cholesterol levels, supports telomeres, improves resistance to illness, reduces cravings, improves body composition, and slows the aging process. And makes millions for distributors who got on the bandwagon early and are high on the pyramid.

I have written about it before and have been roundly criticized by its proponents.   It generated my all-time favorite insult: “Dr Harriet Hall is a refrigerator with a head.”

My biggest concern with Isagenix was that it had not been clinically tested. They claimed that clinical tests were in progress (funded by Isagenix).  An e-mail correspondent recently told me I should take another look at Isagenix, since a clinical study had been completed. It had not yet been published, and I asked her to get back to me when it was. Ask and you shall receive (but you may be sorry!). She contacted me when the study by Kroeger et al. was published in the journal Nutrition and Metabolism.   The full study is available online and I urge readers to click on the link and look at Table 2, which I will be referring to later. The journal is peer-reviewed but, as will become painfully obvious, the peer reviewers did not do a competent job. It is an open-access online journal with a low impact factor. The authors had to pay to get their article published: it cost them $1805.


Now, if you were going to design a clinical study of Isagenix, how would you go about it? You probably wouldn’t want to study telomere support or “improved energy” first, or try to establish that “detoxification” had occurred. Since the most common use of Isagenix is for weight loss, it seems to me the logical place to start would be to study weight loss on the Isagenix program compared to weight loss with a diet providing an equal number of calories, ideally a nutritious diet with a similar proportion of fat, carbs and protein.

For some inscrutable reason, these researchers elected to study 54 obese women age 35-65 (no men or younger women or overweight but non-obese women) on a one-day-a-week intermittent fasting (IF) program. They compared a calorie-restricted diet with a liquid meal replacement for 2 meals a day (using only one component of the Isagenix system, Isalean shakes) to a diet with the same number of calories provided by regular food. For the first two weeks, they established a baseline by having patients simply try to maintain their weight. Then for weeks 3-10 they were randomized to the liquid meal replacement Isalean group or the regular food group; and weight, intake, lipids, adipokines, and other factors were measured at weeks 3 and 10.

Why intermittent fasting? In their Introduction, they say that IF has been growing in popularity and that it “may” be effective for weight loss and coronary risk reduction. The references they provide do not show that intermittent fasting offers any advantage over constant calorie restriction. And IF is not a part of the Isagenix program. Why did they choose to incorporate it into their study? Doesn’t it just add another unnecessary complication?

The researchers themselves pointed out a serious limitation of their study. It did not control for food intake. The dinner meal for the Isalean group and all meals for the food group were left up to the subjects after instruction by a dietitian. The goal was to limit breakfast and lunch to 240 calories each and dinner to 400-600 calories, with <35% calories from fat and 50-60% from carbohydrate. Actual intake was self-reported via telephone: subjects were interviewed and asked to recall what they had eaten in the previous 24 hours.


The results were positive, but far from impressive. Over 8 weeks, subjects using Isalean lost 4 kg compared to 3 kg in the control group (1.1 and 0.8 pounds a week, respectively). The Isalean group reportedly reduced their total daily calorie intake from 1708 to 1255, and we can calculate that a reduction of 500 calories a day should result in a weight loss of one pound a week without any need for fasting days, meal replacements, or supplements. The control group reduced their total calorie intake by less than 500 calories a day, so of course they lost less weight.

There were favorable changes in lipids and adipokines, so the researchers argued that that the liquid meal replacement might confer protection against coronary heart disease. That is nothing but speculation, since they didn’t assess actual CHD. We know that measuring changes in risk factors is not enough. For instance, intervention producing favorable changes in the cardiac risk factor homocysteine does not translate to any decrease in cardiac events.

Possible Bias

We know that studies of pharmaceuticals are more likely to generate positive results when funded by the manufacturer. This study was funded by the Isagenix company, and at least one investigator had links to the company.

The Numbers Don’t Add Up

The researchers said that:

Energy intake decreased (P < 0.05) in both the IFCR-L and IFCR-F groups between week 3 and 10. There were no changes in fat, protein, carbohydrate, cholesterol, or fiber intake from the beginning to the end of the study in either group.

I puzzled over the numbers reported in table 2. They just don’t add up. For instance, the total calorie intake for the Isalean group at week 10 was 1255, but if you add up the calories from the reported intake of fat, carbohydrates and protein (9, 4 and 4 calories per gram respectively), you get 1655. Similarly, the total calorie intake for the food group was reported as 1444, but adding up the calories from fat, carbs and protein gives 1279. The Isalean group reportedly ingested more fat, more protein, and more carbohydrates than the regular food group, which would have to mean they got more total calories, not less. I asked my correspondent, who answered:

Our team did notice the inconsistency. They asked the lead investigator who replied that the kcal value for IFCR-L week 10 comes from the 24-h recalls that were analyzed and not from the macronutrient values. It’s unclear why the numbers don’t match up. However, the kcal value for IFCR-L week 10 does make sense in terms of weight loss.

She asked if that answered my question. I replied:

No. Where did the macronutrient values come from? If it is “unclear why the numbers don’t match up,” why were they reported that way, and why can’t the researchers make it clear? What do you mean when you say the kcal value for IFCR-L week 10 does make sense in terms of weight loss? If the calculated values are questionable, how can any conclusions be drawn?

So far, I haven’t received any answer. Apparently her “team” was pacified by the researcher who managed to baffle them with bullshit. When you want to believe, you may be easily convinced that the researcher knows what he’s doing.

More Problems

The subjects in the Isalean group supposedly got 240 calories from each of two Isalean shakes and then ate a 400-600 calorie dinner. That would add up to a daily total of 880 to 1080 calories, not the 1255 calories reported. The food group was intended to ingest the same number of calories, not the 1444 reported.

In the Isalean group, the fat intake was listed as 51 grams (459 calories); but according to the product label, each Isalean serving provides 50 calories from fat, and the goal of <35% calories from fat in the evening meal would give up to 35% of 600 calories or 210 calories from fat. That adds up to a maximum of 310 calories from fat, not an average of 459. If the food group was getting 1444 calories a day and their diet contained 50-60% calories from carbs, their carbohydrate intake ought to be between 722 and 866 calories, not the 696 calories from the 174 grams that were reported.

The more I looked, the more problems I found. Eventually my brain started to melt and I gave up. There’s no way to make sense of the results as reported.

Their Conclusion

Taken together, our results suggest that IFCR (intermittent fasting/ calorie restriction) with liquid meals is an effective diet therapy to reduce body weight, visceral fat mass, and lipid indicators of CHD risk. Our findings also demonstrate that the beneficial modulations in vascular disease risk by IFCR may be mediated, in part, by reductions in visceral fat mass and pro-atherogenic adipokines. This study is an important first step to understanding the underlying mechanisms that mediate the cardio-protective effects of this novel diet regimen.

My Conclusion

The results are uninterpretable. This study does nothing to suggest that the Isagenix system has any advantage over other calorie-restricted diets. Neither does it tell us anything about the possible benefits of intermittent fasting. And the study is not “an important first step to understanding the underlying mechanisms that mediate the cardio-protective effects of this novel diet” since it has not been established that there are any cardio-protective effects to understand.

Posted by Harriet Hall

Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.