Should You Try That New Diet?

One question I am often asked is, “What do you think of XYZ diet?” Every week it seems like a new “scientifically-based” diet is being proposed by the latest expert or pseudoexpert who claims to have the pulse on what really works for weight loss. No wonder people are confused. If your head is spinning at this vertiginous onslaught of contradicting advice, I have a simple method that can help you find the best weight loss approach for YOU. It is the 4 Question "BS" Test.

1. Can I eat this way for the rest of my life? The answer must be yes.

This is the most important question. If no, the remaining questions are moot. If the diet being proposed is one that will be impractical to stick to over the long haul (even if you think you could pull it off for a few months) then it will not be effective for long lasting weight loss. Whatever you do to achieve a healthy weight you must continue to do to preserve that healthy weight. If your answer is no, put the book down.

2. What is the background of the person writing the book?

If the book author does not have extensive experience either in clinical practice relating to weight loss or in the science of obesity, nutrition or exercise, take their advice with a grain of salt.

Healthy lifestyle is a space that a lot of people are trying to capitalize on for 2 reasons. First, the diet industry is a billion dollar industry and growing. Much money is to be made. Every Tom, Dick and Harry will be throwing his hat into the ring. Second, because most people have experience eating, trying to get motivated to exercise, and managing their weight, it gives them a sense of having developed an expertise. It is the “what worked for me will work for others” mentality. If I have learned anything from working with patients for over a decade it is that people are different. Some of my patients love the low-carb diet and have been very successful with it, others hate it and have had great success with low-fat diets. An author who is more interested in making money than being helpful will probably force a one-size-fits-all approach.

3. Is exercise an afterthought in the book?

Exercise must be an integral part of any weight loss program.

I have noticed that many weight loss books focus heavily on the mechanics of a specific diet. They usually mention exercise but do not devote much page time to how to develop a physically active lifestyle that is fulfilling and effective. I find this approach suspect as exercise is as important to weight loss as diet. Some confusion exists as to the role of exercise in weight loss because studies show that exercise by itself does not result in large weight loss. This finding is true but has been so often misinterpreted to mean that exercise is not important for weight loss. On the contrary, studies show that one of the strongest predictors of long-term weight loss is exercise (e.g., Jakicic et al 2008). The most effective approach to weight management is one that combines diet and exercise. If your diet book isn’t acknowledging this, pass on it.

4. Does the book refer to research that shows large weight losses (30+ pounds) over fairly short periods of time (6 months or less)?

I smell a rat.

One trick that many self-help authors use to capture their audience is hand-picking studies that have extreme findings. Interestingly, it is usually the case that we haven’t heard of this research until reading about it in this book. We haven't heard of these studies likely because they have not been well recognized due to significant methodological flaws that challenge the validity of findings. Just because a study has been published does not mean it is sound.* If a very sound, groundbreaking study exists that showed huge weight loss, we would all have heard about it. I stay abreast of this research on a daily basis and I will most definitely blog about any sound, groundbreaking studies that you would find informative.

The next time your coworker tries to convince you to try the latest diet on the bestseller list, try the BS test. I would love to hear which diets pass and fail for you!

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*Related, just because a study is flawed doesn’t mean it should not be published. Some methodological flaws are unanticipated, but researchers can learn a lot from reading about various factors that flaw a study. We try to learn from our own and others mistakes, so there is some utility to reporting the train wrecks. Unfortunately, train wreck data can sometimes get misinterpreted or manipulated.

¹Jakicic, J., Marcus, B, Lang, W, Janney, C. (2008). Effect of exercise on 24-month weight loss maintenance in overweight women. Archives of Internal Medicine, 168(14), 1550-9.