The Shred Diet: A Minimally Kooky Way To Lose Weight


With New Years’ weight loss resolutions freshly made, let’s take a science-based look at another of the latest diet books being promoted by various public relations agencies. In my last post we explored the claims made by the hysterical Eat To Save Your Life authors in their book featuring a demonic cheeseburger on its cover jacket. Today I will review, Shred: The Revolutionary Diet ‚ 6 Weeks, 4 Inches, 2 Sizes, by Ian K. Smith, M.D.

I’m not sure what images the word “shred” conjures up for you, but if they have anything to do with muscle-bound, uber-lean bodybuilders on steroids you will be pleased to note that this book has nothing to do with them. In fact, what you’ll find in this book is a rather practical and healthy eating and exercise prescription with recipes and careful calorie counting. You’ll also find one fairly harmless chapter of liver detox pseudoscience, and an odd command to stare at yourself in the mirror at the beginning of week six.

Quietly stand in front of the mirror, and look deeply into your eyes as if you’re trying to see all the way into the depths of your soul… [p. 167]

The purpose of this visual exercise is never explained.

Since our purpose here at Science Based Medicine is (in large part) to evaluate medical claims, I will spend the remaining paragraphs focusing on the “cleanse” phase of the diet since that is the major area of scientific controversy. Shred’s week five is devoted to “eating particular foods and drinking certain beverages that naturally activate enzymes in the liver to enhance the detoxification process.” As detox regimens go, I was pleased to find nothing of harm here (I had braced myself for an exploration of coffee enemas, high dose vitamins, and extreme laxatives). Dr. Smith’s detox plan includes one daily cup of each: lemon water with flaxseed oil, cranberry juice, and hibiscus tea.

The claims? Doing this will “cause your gastrointestinal tract to move better, your energy levels will increase, and your skin will even appear healthier (some have said that it takes on a certain glow).”p. 126. So what we have here is an exceedingly mild “detox” regimen with very soft clinical endpoints that are difficult to measure objectively. 

But just for fun, let’s take a look at the potential liver enzyme influence that these 4 detox ingredients might have: hibiscus flower, lemon juice, cranberry juice, and flaxseed oil.

1. Hibiscus sabdariffa

The hibiscus plant (hibiscus sabdariffa is used to make tea) contains over 88 different chemicals, according to Dr. Duke’s Phytochemical and Ethnobotanical Databases. There is nothing particularly noteworthy about the plant’s chemical makeup, other than that it contains a significant amount of vitamin C. A review of the PubMed database revealed a smattering of small, animal and in vitro studies linking hibiscus to inducement of rat testicular atrophy and decreased hematocrit when exposed to very large doses. Hibiscus extract was found to be somewhat bacteriostatic in vitro, possibly because of its acidity.  One human study of the effects of drinking hibiscus tea was presented at a medical conference. The study, sponsored by a tea company, found that hibiscus tea consumption could reduce systolic blood pressure by an average of 8mmHg in mildly hypertensive adults. The study included 65 participants in a 6 week placebo controlled trial. 

So as far as hibiscus tea is concerned, there is almost no evidence to date of its usefulness as a liver enzyme stimulator. In large doses it has some possible toxicity in rats, and in humans it may have a blood pressure lowering effect – which is interesting, but unrelated to Dr. Smith’s claims.

2. Lemon juice

In terms of the potential therapeutic effects of lemon juice, kidney stone prevention is probably the most well studied. Lemon juice is an excellent source of vitamin C, which is important for general nutritional needs.

Grapefruit is known to be an inhibitor of certain liver and intestinal enzymes that help to break down medications. Luckily, this is not a citrus “class effect” but is related to a compound unique to grapefruit.  As for lemons, they seem to have no major effect on the liver.

3. Cranberry juice

Although there was some initial enthusiasm years ago about the potential for cranberry juice to reduce urinary tract infections in women, follow up studies have not found cranberry juice to be more effective than placebo. At least one small study suggests that overweight women experience an improvement in lipid oxidation (a risk factor for heart disease) with consumption of two cups of cranberry juice per day. Cranberries, like lemons and hibiscus, contain vitamin C and therefore have anti-oxidant and pro-collagen synthesis properties. As far as direct liver enzyme influence is concerned, I found nothing in the medical literature to support that claim.

4. Flaxseed oil

In theory, flaxseed oil could have anti-inflammatory effects in vivo. A recent study found no change in inflammatory markers or clotting pathways with 8 weeks of regular intake of low dose flaxseed oil. Some studies have noted a decrease in serum LDL cholesterol levels with daily consumption of flaxseed oil. Most experts agree that the desirable anti-inflammatory properties of omega-3 fatty acids are experienced in vivo via consumption of marine sources of omega-3’s only. This is because the chemical properties of fish oil and flax seeds are not biologically equivalent. While flaxseed oil may reduce LDL cholesterol, fish oil is a much more potent source of healthy omega-3 fatty acids. As far as liver “detoxification” is concerned, that does not seem to be a primary benefit of flaxseed oil.

As for the claims of “improved gastrointestinal movement” – small amounts of vitamin C, water, and plant oil are probably not going to make a noticeable difference – at least, not taken by mouth as prescribed by Shred. A “healthier, glowing skin” might be a real benefit of increased vitamin C intake in dieters with true deficiency (think scurvy) – but for those of us who are currently meeting our vitamin C needs, the excess will be excreted (as are all water-soluble vitamins) in our urine. As for the “increased energy levels” I can’t see any reason why citrus or flaxseed would provoke that response, unless you count the increased effort it will take to make a few extra bathroom breaks to relieve oneself of all the tea and juice.

And so, without further belaboring the point, I think we can safely say that Dr. Smith’s liver detox week is little more than hand waving and some increased fluid intake. 

That being said, the recipes, diet plan, and exercise prescriptions in Shred are quite sensible. Eating is organized into four, calorie-controlled meals and three snacks at regularly scheduled intervals throughout the day. Alcohol and soda are limited. The diet is rich in fruits, vegetables, whole grains, lean proteins, and healthy fats. Sugar and refined carbohydrates are avoided. Cardiovascular exercise is recommended for at least forty-five minutes per day, five days a week. The plan is presented in such detail that one can follow instructions for each meal, snack, and exercise every day for six weeks. You simply repeat the six week “course” (perhaps skipping the detox section and the part about staring into your eyes in a mirror) as many times as you like to achieve your total weight loss goal.

In my view, the Shred diet, is a reiteration of sound nutritional and exercise principles in an easy-to-follow menu format that requires little thought processing. If it didn’t wander off into the liver detox fantasy world in chapter five, it would be a sensible book indeed. 

Shred: The Revolutionary Diet – 6 Weeks, 4 Inches, 2 Sizes is now in hardcover and Kindle editions from


Posted in: Nutrition, Science and Medicine

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13 thoughts on “The Shred Diet: A Minimally Kooky Way To Lose Weight

  1. tgobbi says:

    OK, I haven’t read the article yet but, looking at the cover of the book, I have a question. Dr. Smith has a new diet book that’s supposed to work wonders. He had written an earlier diet book that, presumably (I’m unfamiliar with it), also should have worked wonders. So, my question is: if the advice in the first book worked, what’s the need for a new book? (Other, that is, than to make a bunch of money)…

    Perhaps when I get around to reading Dr. Jones’ article later this morning I’ll find that my question has already been answered?

  2. windriven says:

    “You’ll also find one fairly harmless chapter of liver detox pseudoscience, and an odd command to stare at yourself in the mirror at the beginning of week six.”

    I read this and my eyes rolled back in my head. How much pseudoscience is allowed before it crosses the threshold from harmless to … not? Hibiscus sabdariffa is OK p.o. but not as an enema?

    IMO, this guy and Oz are different only in degree, not in kind. Dr. Smith is a veritable Dean Koons of weightloss books: EAT: The Effortless Weightloss Solution, Shred: The Revolutionary Diet, The Fat Smash Diet, Extreme Fat Smash Diet, The Four Day Diet, The Take Control Diet,and his latest blockbuster, The Truth About Men: The Secret Side of the Opposite Sex.

    I think Oz should have him on.

  3. Janet says:

    I don’t care how good his basic advice is–none of it will “work” unless you do it for the rest of your life. Following a regimen from a book for the rest of your life, that includes 45 minutes a day of cardio, doesn’t seem very doable. General principles are there for anyone to easily glean–eat good food, not too much, mostly plants (Michael Pollan).

    These books do nothing but make money for their unethical authors preying on people who haven’t found the gumption to restrict their calories on a consistent basis by eating sensibly and admitting that you cannot have a “treat” every time you get up off the couch. They think buying the book will “inspire” them or reveal the “trick” to losing weight. The authors know this and use this psychology to make money–nothing more. That this guy has MD after his name is just a sign that it doesn’t always mean that medical school picks the “best and brightest”.

    Off Topic:

    I’d like one of you to take on the woo that surrounds skin care/cosmetics. Lately, whenever I visit a cosmetic counter (such as perfume purchases at Christmas) I get into some very exasperating back-and-forths with the women who work for these companies. They make outrageous claims (expected) and then further claim it is all “clinically proven” when you raise your (perfectly penciled) eyebrows. Usually, the mention of counter-advice from one’s dermatologist shuts them up, but not so much lately–perhaps I am getting more adversarial in my criticisms?

  4. DugganSC says:

    While I can’t imagine it’s the effect that Dr. Smith is looking for. staring into the mirror for a prolonged amount of time tends to invoke the Troxler effect, which is the source of various “scrying” tricks and the old Bloody Mary legend. Basically, as you stare at your face in the mirror, the brain starts to block out the parts of the scene which haven’t changed and fill in the missing bits with whatever’s going through your head. Typically, the eyes remain due to the small movements we’re always making, which means most viewers wind up with their own eyes set into a monstrous face. Supposedly, what you see is as interpretable as any dream psych-wise.

    Me, I just get eyes and sometimes not even that… no idea what that means other than potentially an empty mind. :-P

  5. windriven says:


    Great topic! Cosmetics are a multi-billion dollar industry in the US* and many of them claim clinically proven results. So where is this clinic? The lunchroom at Max Factor? Is MAD Magazine considered peer reviewed?

    *I tried to find a good and credible source for annual revenues but found numbers ranging from 2.8 billion to 38 billion.

  6. windriven says:


    I suffer from too short an attention span for the Toxler effect to manifest itself. After about 180ms I’d think, “sh*t boy, you really need to lose a few pounds” and walk away before I felt compelled to hit the treadmill.

  7. Calli Arcale says:

    “Although there was some initial enthusiasm years ago about the potential for cranberry juice to reduce urinary tract infections in women, follow up studies have not found cranberry juice to be more effective than placebo.”

    Nevertheless, this claim remains a useful justification for ordering a cranberry mimosa with brunch. :-D

    (Seriously, try it! Cranberry mimosas are awesome. The flavors really go together well. Better than orange, IMHO.)

  8. CarolM says:

    Duggan, personally I think I look fabulous in a dimly lit room, and don’t get this Troxler effect at all. ;)

  9. stellaluna says:

    Regarding the cosmetics suggestion – there is an excellent source for the shredding of all things cosmetically woo already (see what I did there?). Paula Begoun wrote a book entitled “Don’t Go To the Cosmetics Counter Without Me” in 1992, which explained the science (or lack thereof) behind cosmetic claims and ingredients.

    She started her own line of products that used to be very inexpensive, in plain black and white packaging with zero hoopla. Unfortunately, in recent years her company has dressed up the packaging, exclamation-pointed the product descriptions, and raised prices. That said, she continues to only use ingredients that either have some efficacy or that are needed to maintain the formulation and keep it sanitary. Her website continues to review other companies’ products and rate them on claims v efficacy, as well as on price. She identifies lower priced products that are just as effective, or more so, than higher priced ones and provides footnotes and links to the studies that show what the ingredients do.

    (You can tell from my tone that I’m disappointed that her marketing changed. She used to differentiate her stuff with a “science-based, and because there are no magic bullets this is also appropriately affordable” presentation. Now she has a Shazam! presentation and a more upscale pricetag which, to my mind, undermines my confidence even though the products do what they say, and don’t promise to do that which can’t be done.)

    Anyhoooooo, I still primarily use her skincare products or those which I check out on her website regarding the ingredients….check out her pages at PaulasChoice dot com.

  10. WilliamLawrenceUtridge says:


    Chances are she ran into what most honest* SCAMmers did – simply couldn’t make enough money off of staying honest, and had to market differently. Most people buy SCAMs for the hope, which good marketing supports, not for the science. Looks like a good accountant** got hold of her business model and did what s/he could to make it more profitable. For instance, the increased price could be seen as paying a premium for an honest product, akin to buying “cruelty free” eggs.

    One of the reasons doctors remain a financially viable profession is that it is to a large extent protected from competition by things like the FDA, which also works to ensure their claims are justified, and thus effective.

    *in terms of genuinely believing what they do, but sticking to what they can treat with science; of necessity a small number
    **defined as someone who helps you make more money without either of you ending up in jail

  11. Janet says:


    Thanks for the thumbs up–and your question is exactly what I asked the latest little airhead that mentioned “clinical results”–actually I said, “spelling is CliniQUE doesn’t make it a real “clinic”.

    @ Stella

    I read that book and several others (mostly by science-based dermatologists–which can be difficult to come by) that opened my eyes years ago, but as you report, she has largely sold out, so….. Anyway, this industry needs constant myth busting. It may not be a life-threatening issue, but it’s a good place to start for getting people, mostly women, to think critically.

    Cosmetics is an area where I think the FDA would be more helpful if they promoted listing the ingredients by their common names. The chemical cocktails on the packages are fairly meaningless to anyone without a chemistry degree, although the first ingredient (no matter the cost) is usually WATER–omigosh, am I actually putting homeopathy on my face?!

    By the way, I only buy the sunscreen, because they have a tinted one and I have vitiligo, so it works (cosmetically) a bit better than the drugstore stuff. I wash my face with, –gasp!– soap and use a cheap moisturizer. Yes, I wear makeup sometimes, but what I have lasts me for years. If we could attach pictures, I’d send one just to prove I look good without much cosmetics or any overpriced skin potions. :-) A kindly dermatologist told me when I was 40 (and requesting panic-stricken advice) to do two things: Use sunscreen and get a big hat. I took his advice.

  12. Pat says:

    I have tried many techniques to lose weight. Dr. Smith is 100% accurate with the diet confusion approach. My first week 2 pounds down and feeling great. That’s with eating chocolate as a “snack” attending a Food/Wine Festival.

    An hour of exercise is a breeze when you are eating healthy. Different approaches for different people but in my opinion everyone can do this.

    Pessimists need to be careful of their discouraging remarks.

    Thanks Dr. Smith!!

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