Low Carb is for everyone. This has to do with carbs. If someone has high body fat percent, this is because the fat from meals whether is from fats or carbs spilling over…is staying stored causing a calorie surplus. The body only needs a certain amount of energy (food). People with high body fat usually over feed on carbs because carbs are everywhere, which makes it safe to assume they are always storing sugar as fat and signaling insulin. This plus, the insulin response due to the surplus causes chaos. Low carbs is great for people that have consumed carbs for too long, so they can down regulate glycogen and insulin. People with low body fat usually depend on muscle and muscles store glycogen. So these people would benefit from high carbs until it’s time to back off.
Most problems with the hip flexors, however, don't originate in a lack of strength but in a lack of flexibility. To understand how these muscles lose their flexibility, imagine someone with a broken arm, her bent elbow encased in a plaster cast. When the cast is removed after six or eight weeks, the soft tissues around the elbow (muscles, tendons, ligaments, and even skin) will have shortened, and the elbow won't straighten out. It will take patient stretching over several weeks to restore the range of motion. Similarly, if the hip is constantly kept in a flexed position—like sitting—for hours every day, day after day, the hip flexors will shorten and shrink, limiting your ability to fully extend (straighten) the hip.
Note that this recommendation is for total weekly volume, which means it would need to be divided up based on how many times you’re training each muscle group per week. So, for example, someone training everything twice per week would do 30-70 reps for each bigger muscle group in each of those workouts, and 15-35 reps for each smaller muscle group in each of those workouts.