Body Composition

Losing body weight (actual body mass, not just daily fluctuations based on water retention, etc.) means losing some fat and some muscle. Rarely (except given certain factors, conditions, time periods, etc.) does someone losing weight lose only fat. When losing weight we can influence the degree of fat loss and muscle retention by how we train, eat, and sleep (which is how we influence body composition even when we are not losing weight). Yes there is a genetic component (everything else being the same — which it rarely is — some are more predisposed towards fat retention than muscle retention), but regardless, the most impactful factors remain training, eating, and sleeping.

Strength training (done properly, of course ) when losing body weight gives your body a reason to hold on to muscle, just as strength training when not losing body weight gives your body a reason to build muscle. Relatedly, the natural muscle loss associated with aging can also be influenced by strength training (and the other factors) because you continue signaling your body that it needs muscle and to be strong. Yes some internet arguers may argue that by technical definition that the uses of muscle and strength in the previous sentences may not technically be interchangeable. But at least in this case we can ignore the internet arguers and keep things simple and practical and effective (while also yes, still remaining scientific and accurate).

Losing weight does not require exercising. But because of how healthy and beneficial exercising is (even in the absence of losing weight), everyone should do it. Losing weight means losing some muscle. But because of how healthy and beneficial muscle is (even in the absence of making other changes), retaining muscle while losing weight should be a priority. The benefits of muscle are many but they are not the focus of this piece.

Many bodies affected by excess weight are primarily affected by excess fat (not excess muscle). Minding (and in some cases, focusing on) body composition can be at least one healthy and helpful and important part of the process. Bodies do not lose weight or fat and or build or retain muscle unless they are told to. One fantastic way of telling your body to change and look and feel and function the way you are wanting it to, is with strength training.

June 2025