Quote:
Boosts to your energy levels through caffiene, for example, may actually not help in the long term.
This actually isn't true. Caffeine, particularly in supplement form, has been used for a long long time to increase sports performance. People who have ingested it can perform their workouts at a higher intensity for a longer period of time. That'll improve physical fitness more than forcing through for a while, meaning you'll be more fit at a faster rate. It doesn't have many benefits for short term exercise (like sprinting) but improves endurance on longer bouts. Obviously, exercise longer = bigger calorie deficit = more weight loss, which will probably help a lot more with the tiredness than any supplement.