There’s a general equation in popular culture which says that the less body fat you have, the healthier and fitter you are. This is simply not always true. However, because it squares with a cultural desire that bodies be lean in order to be sexy, it has become the dominant belief when it comes to weight. Body fat’s role in our health is more complex than this and what amount you should have is not a black and white issue, it’s a nexus of factors.
Body Fat Can Play A Positive Role In Your Body’s Performance
We are well acquainted with the negative sides of body fat. Less discussed are the important positive roles it plays in our physiology. Fat is not just an inert storage material. These days, adipose tissue is recognized as an organ belonging to our endocrine system. It plays a vital role in the secretion of hormones, helps regulate energy and body temperature, facilitates the movement of muscles, and protects internal organs.1 This is why having too little body fat can be just as damaging as having too much. For example, low body fat in both sexes can cause disruptions in proper hormone levels, lead to weakened immune response, decreases in muscle function, and more. In women, it can disrupt menstrual cycles and weaken bones, both of which can have negative effects that stretch far into the future.2
In the athletic realm, body fat sometimes plays an important role as mass, i.e. the kind of mass in the physics equation F=MA. Football linebackers are examples of athletes who benefit from being heavier for obvious reasons, but it isn’t just them. Heavyweight competitors in many sports such as boxing, weightlifting, wrestling, and martial arts also need extra weight because generating force to move large loads, be they weights or opponents, requires mass. This is why the heaviest of heavyweight athletes are almost never ripped. In spite of our image of the athlete as lean and muscular, for some it just doesn’t pay to be that way—in fact, it’s a detriment.
Contrary To Common Wisdom, There Are No Standards For Obesity
The word obese has basically become a synonym for ‘fat’ in popular culture, but when it comes to health, deciding what ‘obese’ means is a lot trickier than most of us think. The World Health Organization (WHO) defines obesity as “abnormal or excessive body fat accumulation that may impair health.”3 The problem though, is that there is no way to clearly define how much body fat that is.
It’s not uncommon to see guidelines stating that a body fat percentage of over 25% in men and over 35% qualifies as obese. However, it has been pointed out that these numbers are actually based on a misinterpretation of a World Health Organization technical report from all the way back in 1995. According to researchers who raised the alarm, the WHO technical report in question was actually referring to a Swedish study that reported average body fat measurements of middle-aged Swedes. The WHO never proposed these numbers as some kind of cut-off point with regards to defining obesity.4
Of course, the motivation for having cutoff points in the first place is so that, in theory, we’d be able to say that after crossing such-and-such a line your health will be negatively impacted. The problem is, even when we do use some general statistics about when body fat becomes more likely to “impair health”, as soon as we get down to the individual level, all those guidelines can change. Depending on individual factors like age, sex, athletic pursuits, or morphology, any guidelines we create can be useless when applied to a specific person. That’s why, as of now, there are no official, universal cutoff points for obesity. Research suggests instead that we leave defining “obesity” to the judgement of a physician evaluating an individual patient.5
Obesity As A Health Metric Is Different Than Wanting To Be ‘Skinny’
There is of course still such a thing as having too much body fat. However, all too often losing body fat is viewed as always positive. This is an oversimplification. Body fat is not, contrary to popular opinion, bad by default.
How much body fat one should have really depends on who you are and what you are trying to do. Heavyweight athletes, for example, need to be heavy and, moreover, have usually become heavyweights precisely because they are naturally bigger to begin with, which has been a boon to their athletic career. Older individuals may have more body fat than their younger selves because that is what their body needs at their age. Women need a certain level of body fat to maintain a healthy hormonal balance, especially because it has such profound influence on long term health issues like bone density. Larger individuals of any age may be perfectly healthy depending on what their individual morphology dictates is right for them. There simply is no exact formula, especially not one that says leaner always equals better. In a culture that tends to view body fat a constant enemy, this can be easy to forget.
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Additional: More On Body Fat Cutoff Points – Reply