By Krista Scott-Dixon, PhD

Right off the bat, Brenda Watson's book The Fiber35 Diet makes me a little nervous. In part, it reminds me of my mother, science teacher, and nutritionist (all wrapped up into one), also known as the "Fiber Queen." She used to solve nearly every stomach ailment by proffering one of her "magic muffins" with the exhortation: "Have one... it'll help you have a B.M (bowel movement)." Over the years, my mother's fibrous ferocity became legendary.

Latent mother issues aside, however, this is not the biggest problem I have with the book. It's that it is chock-full of all the "danger" words and concepts that tell a reader to beware of diet scams. This is a shame, because Watson's message overall is a good, well-grounded one: Get plenty of soluble and insoluble fiber from fruits, vegetables, and whole grains, eat reasonable portions, and exercise. The problem is that this excellent, evidence-based message is buried in hyperbolic language and often dodgy advice.

The Fiber35 Diet and the Red Flags

For one thing, I always caution readers to be skeptical when presented with diets based on single macronutrients (such as raising or lowering the amount of fat, protein, or carbohydrates). Humans are omnivores with relatively varied diets. Simply focusing on one ingredient rather than considering the diet as a whole is misleading and not representative of how humans actually eat.

Second, my red flags immediately go up when I see words like "magic", "revolutionary", and other superlatives. The book is liberally peppered with statements such as "medical miracle"; "secret ingredient"; "change your life forever"; "gift of fiber", "greatest medical discovery" and so forth. And those examples are from the first two pages. What is the "secret formula" for lifetime weight management and disease prevention, asks Watson. Why, it's 35 grams of fiber a day. "If I were on my deathbed," she writes exuberantly in the introduction, "and a higher power said to me, ‘You can share one more message with the rest of the world. What will it be?' You guessed it: Eat 35 grams of fiber a day!" (8)

Now, if 35 grams of fiber a day were all that stood between me and a size 2, I would not have eaten my way up to 50 pounds overweight on a low-fat, high-carb diet in the early 1990s. I was into the Ornish plan at the time, and eating so much fiber I began to experience mild agoraphobia whenever I had to leave the house and a proximate bathroom. Plus, I was constantly ravenous. If 35 grams of fiber alone could keep disease at bay, the "Fiber Queen" would not have had colon cancer and the "Fiber King" would not have had two heart attacks. To be fair, the 35 grams come from good sources, but it is no miracle.

Third, Watson favors a highly restrictive initial diet phase, with calories as low as 1200 per day, with often confusing caloric calculations. Calories should be calculated based on several factors including bodyweight, age, sex, activity levels, and beginning levels of body fat. Younger people; men; highly active people; and people starting out relatively leaner need a higher caloric intake. Set your watch: If you want to see a binge in 7 days, make a 300 pound person eat 1200 calories for a week. Rapid weight loss is also associated with loss of lean body mass, which should be minimized as much as possible. You need that stuff. Puzzlingly, while Watson provides this information, she includes it only for weight maintenance, not weight loss.

An initial restrictive phase is generally unnecessary, except perhaps to get dieters excited about success, but early restriction carries a very significant risk of relapse into the food behaviors that caused the problem in the first place. Early meal plans consist mostly of prefabricated fiber-protein snacks and shakes rather than real food.

The Fiber35 Diet's Sound Advice

Much of Watson's advice is sound. She points out that we need to consume fewer calories than we expend through activity in order to lose weight. She emphasizes the immense nutritional importance of fruits and vegetables and their constituent phytonutrients. She explains the mechanisms by which fiber and fiber-containing foods can help improve disease markers (such as lowering bad LDL cholesterol), immunity, and satiety (feeling of fullness), while helping to control appetite and blood sugar. I put a nice big checkmark next to the section where Watson lays out the macronutrient ratio: 25% protein, 25% fat, 50% carbohydrate. Not ideal for everyone, but a pretty decent start for the average person, especially if those carbs are coming from fibrous sources. I particularly like the exercise advice and emphasis on including resistance training. There are some good recipes included. Additionally, Watson does a nice job of encapsulating the key points of her argument in little summaries at the end of each chapter.

Unsubstantiated Claims

Often Watson's claims are well-backed with scholarly and clinical evidence. But then, there's some stuff that is not quite as solidly supported. For example, she claims that "thirty minutes in a sauna is like running a five-mile race." If this were true, then warm climates would have no heavy people. She digresses into a long discussion of "toxins," a concept enjoying heavy rotation and loose interpretations in health food circles but rather more narrowly defined in physiology circles. "Fat," claims Watson, "is relatively inactive from a metabolic standpoint, and just sits there." In fact, emerging research is demonstrating that fat (adipose tissue) is quite active, even to the point of possibly constituting a separate endocrine (hormone-generating) system.

Unnecessary, Possibly Harmful Advice

Watson really goes off the rails with her recommendation of colonic irrigations, or colonic hydrotherapy (a fancier way of saying "enema") as a way to rid the body of "toxins." The premise here is that the intestines are a kind of cesspool where toxins accumulate, requiring aggressive flushing. Yet evolution has provided many clever and responsive mechanisms for the body to excrete waste. Forcing the procedure on a relatively healthy person is at best unnecessary and at worst actively harmful. Adverse effects such as colon perforations and infections have been reported. As mom would say, perhaps folks just need a good muffin.

The verdict? Good quality advice obscured at times.