September 25, 2009
The Baby. The Bathwater.
By Barbara Berkeley
Ever feel like you’re running a mad dash just to keep up with the latest diet and exercise recommendations? Instant communication is a wonderful thing, but it can be frankly overwhelming when every day brings a new study, a new conclusion and something new to worry about.
The most damaging period in my personal dietary history was the “fat-free” era. It was during these years that I gained 20 pounds while eating “healthily.” For me, the no-fat craze was manna from heaven; the ultimate opportunity to eat unlimited bread and large plates of pasta. So long as the spaghetti sauce was fat-free and the bread had fat-free jelly, I was golden. At first, I was bewildered by the scale. Had a microgram of fat snuck into my diet somewhere? Were the labels wrong? Were those Entenmann’s Fat Free cookies a sham? I was doing it all correctly, following all of the latest rules, yet I was getting fatter by the day!!!!
The fat-free era picked up steam in the 1980s after research pointed to the idea that saturated fat might be making us sick. But since dietary concepts are so complicated, we invoked our usual response to lifestyle advice: throwing the baby out with the bathwater. It was easier to cut out ALL fat thus demonizing one dietary element while elevating another. Suddenly fat was bad. Very bad. And carbs were good. Very, very good.
Of the fat-free days, Dr. Walter Willett of the Harvard School of Public Health has observed: “This campaign to reduce fat in the diet has had some pretty disastrous consequences...One of the most unfortunate unintended consequences of the fat-free crusade was the idea that if it wasn't fat, it wouldn't make you fat. I even had colleagues who were telling the public that you can't get fat eating carbohydrates. Actually, farmers have known for thousands of years that you can make animals fat by feeding them grains, as long as you don't let them run around too much, and it turns out that applies to humans. We can very easily get fat from eating too many carbohydrates, and the public was really directed to only focus on fat calories, when we really have to keep an eye on calories no matter where they're coming from.” (The underlining is mine)
My body certainly recognized the fat-gaining properties of carb loading. Like the fat cells of a corn-fed steer, my adipose tissue responded by swelling exponentially. Now, 20 years later, it’s turned out that we need fat. We don’t have to throw it all overboard. Why do we have to be such diet lemmings? Someone announces a finding and we all run to follow. We really should check to see if we’re going over a cliff before we join the mad dash.
I had a feeling of déjà-vu-all-over-again when I saw the cover of Time magazine on August 9th. At first, I was excited by the topic: The Myth About Exercise.
For years I had been telling my patients to stop putting so much stock in exercise as a weight-loss tool. A steady stream of overweight patients who were also tennis players, weight lifters, and aerobic steppers had taught me that exercise was not the driving force in weight loss. Weight loss was created by caloric restriction and by proper food choice. Period. Finally, a major news source was reporting this observation. In the article, Dr. Eric Ravussin, a well-known exercise researcher from Lousiana State University was quoted as saying, “In general, for weight loss, exercise is pretty useless.” I was gleeful. This sounded like me talking.
To support its point, the article cited a study of 464 overweight women who were divided into four groups. One group was to stay sedentary, while the other three were to exercise with a trainer at various levels (72, 136 and 194 minutes per week). No dietary changes were made. At the end of six months, there was no weight difference between groups. Exercise had not caused weight loss. Other similar evidence bolstered the contention that exercise did not help dieters lose pounds.
Time concluded: “All this helps explain why our herculean exercise over the past 30 years—all the personal trainers, StairMasters and VersaClimbers; all the Pilates classes and yoga retreats and fat camps—hasn’t made us thinner…From a weight-loss perpective, you would have been better off sitting on the sofa knitting.”
This is just the kind of major media pronouncement that gets behavioral stampedes going. After the cover story appeared, I noticed that a number of patients began to reference it as a reason to give up exercise. Did I hear the patter of little lemming feet?
The fact that exercise alone does not cause weight loss says absolutely nothing about the value of exercise to dieters and maintainers. In my experience, exercise is absolutely vital to successfully flipping the lifestyle switch. Exercise builds cardiovascular resilience, improves mood (some studies show it is as good as antidepressant medication), decreases insulin resistance problems, refocuses our attention on staying well and keeps us in a particular kind of connection with our bodies. Like most elements of wellness, the truth about exercise is nuanced rather than obvious.
The month after the Time article came out, a much quieter and less heralded piece appeared in the Mayo Clinic Proceeding. Several major medical centers had cooperated on a study of 3044 women and had followed their fitness since 1971. Each of these women had an early sugar problem, either undiagnosed diabetes or something called “impaired fasting glucose.” The latter term refers to those who have a morning blood sugar of between 100-125. Such sugar problems are extremely common in overweight people.
As I’ve written before, most of the patients I care for have problems processing blood sugar. Patients who I’ve seen in the past, and who return to me years later, will often have developed impaired fasting glucose in the interim. If you are (or were) very overweight, the chances are good that sugar issues were involved somewhere along the line. As you probably already know, sugar-processing problems cause the body to over-secrete insulin: the fat storage hormone. At the same time, muscles (which usually burn sugar) stop accepting sugar as fuel. The result of these two derangements is that blood sugar is diverted to fat . Weight gain escalates and can continue unchecked. For overweight and obese people, studies that look at sugar problems are highly relevant.
The multicenter study followed these sugar-challenged women for 16 years and evaluated their level of fitness by determining how long and intensely they could perform a treadmill test. In the end, less fit women had a greater risk of death from all causes. Most fit women had the lowest risk. This protective effect held true even for women of higher weights. The least fit overweight women had more than twice the death rate of the most fit overweight women. In fact, the importance of fitness was so great that it trumped the effect of BMI as a predictor of death from all causes.
This study is just one of a sea of reports that confirm the profound benefit of exercise. Yet if we focus our sites solely on weight loss, we might easily conclude that exercise is worthless.
With fully two-thirds of us overweight, diet studies make good headlines. But studies were never meant to be read in isolation. In research, each theory and each conclusion must be weighed against the body of evidence that has come before. Individual conclusions may be diametrically opposed. Over time, the weight of one perspective will outbalance another. We must be patient. Unfortunately, this long view is not included in the way diet and nutritional studies are currently promoted. Each new pronouncement makes the front page and is heralded on the crawl under the nightly newscast. Then, we are off chasing the latest theory and the baby is gone with the bathwater.
So, here is some advice for all interested parties. When the latest diet discovery hits, take a deep breath, do your homework. Use common sense. Don’t let the diet-tip du-jour move you from your well-considered strategy. Stick with a life plan that closely mirrors the way man has always eaten and behaved; one that includes plenty of simple, unadorned, natural foods, and simple, unadorned, natural physical movement. Change course only when the weight of significant evidence compels you to institute a thoughtful change of heart.
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