All humans possess the fundamental physiological capacity to achieve fat loss, increases in muscular strength, and muscle hypertrophy through appropriate lifestyle interventions, although the magnitude of these changes may vary between individuals.

Study: Long‐term preservation of lean mass and sustained loss of fat mass after completion of an intensive lifestyle intervention in older adults with obesity and type 2 diabetes

Older adults with diabetes and obesity lost fat and gained muscle after a diet and exercise program, and kept those benefits for months—showing that meaningful body changes are possible for everyone with the right lifestyle habits.

Study: Repeated Resistance Training Reveals the Reproducibility of Muscle Strength and Size Responses Within Individuals

The study shows that everyone who trained got stronger and built muscle over time, even if some improved more than others, which supports the idea that all people can benefit from exercise in these ways.

Study: Links Between Testosterone, Oestrogen, and the Growth Hormone/Insulin-Like Growth Factor Axis and Resistance Exercise Muscle Adaptations

The study shows that lifting weights helps muscles grow in most people by triggering important hormones, which supports the idea that everyone can build muscle with the right exercise, even if results vary.

Study: Physiologic and molecular bases of muscle hypertrophy and atrophy: impact of resistance exercise on human skeletal muscle (protein and exercise dose effects).

The study shows that lifting weights and eating protein help muscles grow in people, even as they age, which supports the idea that everyone can build muscle with the right habits.