A dream about dieting may be referring to some kind of restriction upon you in waking life. In your dream, you may be carefully measuring out food and drink portions, or longing for forbidden fruit. In waking life, have you been measuring out your time or restricting how much emotion you show? Are you holding back your feelings in some way? Similarly, if you overindulged or broke your diet in some way in your dream, are your emotions out of control? Vitamin pills and dietary supplements in your dream may be referring to your health. Does your health need a boost in some way? Are you lacking variety? If you can’t decide which vitamin pill to take in your dream, then perhaps this represents the variety of possible ways in which you can reinvent yourself in real life.
If you were exercising or lifting weights in a gym in your dream, this may be referring to your body image. How easy or difficult you found the exercise may be commenting on your psychological and physical ability to complete a project in waking life.... The Element Encyclopedia
A dream in which you were keeping fit by working out—whether it was in the gym with weights or on an exercise machine, or following an exercise video at home—may be commenting on your real-life need to gain or lose weight.
If you already take good care of yourself and exercise regularly your dreaming mind could have been encouraging you to build up a different kind of strength and stamina; not necessarily physical, but emotional or intellectual.
Alternatively, keep-fit dreams could have been commenting on how you are feeling in real life. For example, if you were running on a treadmill, do you feel that you are expending a lot of energy but actually getting nowhere? If you were lifting weights, do you feel you are shouldering a burden in waking life? If a fitness instructor is yelling at your exhausted dream self, do you feel that you are being pushed beyond your limits by someone who has authority over you in real life? Dreams in which you are practicing or watching yoga may be urging you to take a more flexible approach to life. They may also be encouraging you to step back from outward activity for a while to explore your inner motivations.... The Element Encyclopedia