Someone starts out sedentary, overweight, and somewhat insulin resistant. They set out to improve their health and lose some weight by following a low-carb diet. It works great. They lose weight, their insulin sensitivity improves, and their energy is through the roof. They start exercising, which helps them lose some more weight, as well as build some lean muscle mass. Now they are really into it, and the frequency and intensity of their training increases. This individual is now at a healthy weight (or relatively lean), is exercising regularly, and has better insulin sensitivity. They are a completely different person, metabolically speaking, then when they started. But the problem is they are no longer properly fueling their body and recovering from their intense training sessions (which were once non-existent). They are starting to feel tired and fatigued in the gym, are always in a bad mood, are holding on to stubborn body fat, can’t sleep at night, get sick all of the time, and are maybe having some sexual performance and hormonal issues. Their diet no longer matches their new activity levels and current metabolic condition, because those have completely changed over time. If this person objectively looked at their situation and progress and listened to their own body and biofeedback, they would consider some dietary adjustments. A moderate-to-higher carb intake might be a better fit. But some people will cling to a diet that initially gave them good results, and got them from Point A to Point B, thinking it will get them from Point B to Point C. I’ve been there myself. Part of it is initial experience, part of it is marketing material, and part of it is pure emotion. It doesn’t always work that way for continued progress.