Adam C. Stewart
Most of the goals that I am asked about indicate a specific percentage of body fat as a goal and set a specific deadline for achieving the goals. In this article, I explain why I think both strategies are generally suboptimal and suggest an alternative approach.
Note: This article was the cover of MASS Research Review for January 2024 and is part of their “From the Mailbag” series of articles. If you want more content like this, subscribe to MASS.
This article is not about the exact issue listed above. In reality, these are all kinds of questions that try to achieve a certain percentage of body fat in a certain (and often very short) period of time. I have answered this question countless times during my fitness career, and the person asking the question is hardly ever satisfied with my answer. The truth is that I usually maul this issue because I maul the goal-setting process that it reflects. I never set a specific percentage of body fat as the goal of a diet or a program, preferring flexible schedules rather than a specific deadline to achieve the goals (whenever possible). In this article I explain why body fat goals with fixed schedules are not recommended and offer a better Alternative.
No one cares about your body fat percentage
My first problem with making a specific percentage of body fat your target is related to logical reasoning rather than empirical scientific data. Simply put, no one cares about your body fat percentage (probably you too). In my experience, body fat goals are substitutes (at best) that are supposed to be roughly compatible with the real goal. For example, someone might want to reduce body fat to 20% because their recent blood tests revealed high cholesterol and impaired glycemic control. You might assume that you can keep these blood biomarkers at bay if you are able to achieve 20% body fat, which could indeed be true. However, your goal is not really the body fat percentage; If you had 20% body fat and still had high cholesterol and impaired glycemic control, you would not have achieved the real evaluation criteria that you really hoped for.
Sometimes people set body fat goals for themselves because they think it will improve their athletic performance. For example, a Powerlifter might believe that he would be more competitive in a lower weight class, or an athlete might believe that he would be more explosive if he had a more favorable strength/Mass or strength/Mass ratio. These people might assume that their sports goals would be achieved when they reached their planned body fat percentage, but body fat percentage is again a bad indicator in this scenario. If a Powerlifter reaches his target body fat percentage, competes in a lower weight category, but ends up performing poorly and ranking lower, I doubt he will be satisfied with these results.
Sometimes people set body fat goals for themselves because they think it helps them achieve a certain aesthetic appearance. For example, someone could see a fitness model or a bodybuilding competitor with a desirable physique, estimate that person’s body fat percentage, and then achieve the same body fat percentage. The most common approaches to visually estimating a person’s body fat percentage are either rates or the use of a three-by-three grid of images with estimated body fat ranges. Here’s the problem: the distribution of body fat varies from person to person, and the visual impact of muscle definition depends on the combined effects of subcutaneous fat storage and underlying muscle development. So imagine that you estimated the body fat percentage of a fitness model and used it as a goal. Would you be satisfied if you achieved this percentage of body fat, but you looked completely different due to insufficient musculature? Alternatively, would you be satisfied if you reached that body fat percentage but had absolutely shredded limbs while maintaining considerable fat in your abdominal area? The satisfaction resulting from the achievement of goals is very subjective, but in most matters these hypothetical scenarios lead to more disappointment than satisfaction. Even in competitive bodybuilding, where fixation on body fat percentage levels is widespread among competitors, the emphasis on certain body fat levels is out of place. The thinnest bodybuilder does not always win, and the judges will never ask, measure or know your body fat percentage. The goal of a competitive bodybuilder is to achieve a specific look that balances musculature, symmetry and thinness – it is difficult to win a show rich in body fat, but competitors are better served when they focus on their physique and presentation instead of focusing only on an arbitrary body fat percentage goal.
So if your goal is to improve a health-related metric, set a goal for that health-related metric. If your goal is to improve performance, set a performance goal for yourself. If your goal is to look a certain way, set a goal that focuses on appearance. In all three scenarios, body fat percentage is only an indicator of the true underlying goal, and a bad indicator on top of that.
No one knows what your body fat percentage is
Let’s say you’ve gone through the last section, completely rejected the premise and set a goal to achieve a certain body fat percentage. How would you know if you have achieved your goal?
The most obvious answer is to have your body fat percentage measured. In reality, this is a surprisingly inadequate answer. Measuring body fat is categorically irrelevant; the only way to really measure body fat is by dissecting the corpse, and this seems to me to be a rather extreme choice. Instead, there are many common methods for estimating body fat percentage. The classic estimation methods are underwater weighing and skin fold measurements using calipers.
More modern estimation methods include bioelectric impedance analysis, air displacement plethysmography (BodPod), three-dimensional optical scanners, ultrasound imaging and dual energy X-ray absorptiometry (DXA). Intuitively, most people seem quite comfortable assuming that underwater considerations and skin fold measurements are imperfect methods prone to significant estimation errors. People naturally tend to assume that older methods are less accurate (if this were not the matter, why should we bother to develop new methods?), and it seems rather far-fetched to assume that determining the thickness of the skin folds in certain specific places or determining your body weight in a swimming pool gives an extremely accurate body fat value. On the other hand, people tend to naturally assume that new methods are very accurate, especially when it comes to expensive and technologically impressive devices. Do new estimation methods such as BodPod, DXA and bioelectric impedance analysis provide accurate estimates?
