Its simple.
To gain bulk (muscle mass) you have to adopt a vigorous exercise regime consisting of heavy wieghts and few reps. This way the muscle is exercised at its fullest capacity. An adequate diet of the relevant protein intake is a must to compensate for the wear and tear of the muscles during such regimes, along with proper rest periods. Following this regime will increase the muscle mass.
However, sticking to the question, if weight loss is required without ‘bulking up’ – this can be done sticking to an exercise routine that includes:
1— Cardiovascular exercises such as : jogging, running, cycling etc.
2— Weight training: Workouts with normal weights and more reps (compared to the muscle mass regime). By ‘normal’ I mean anything you can lift easily for 15–20. This way you’d be getting muscle defination (also referred to as ‘cuts’) but wont get beefed up. While exercising, do your reps slowly – dont jerk the bar up and down. Lift it up slowly then bring it back down slowly – this stretches your muscles to the limit.
Other things that should be a part of any exercise regime are:
1— A proper diet: In case of loosing weight – all fat based and sugary foods should be off your menu. You can consume the natural sugars present in fruits.
2— Consume lots of fluids: Water is of utmost importance. Also include Green Tea in your diet- its a good source of anti-toxins. Soft drinks are a strict no.
3— Rest intervals: Ideally you should have a day off between workouts. Because the day you workout – your muscles undergo wear and tear- so giving them a day off to rebuild and recover makes sense.
4— Sleep: Your sleep should never be compromised – since its when your body undergoes muscle recovery and rebuilding.
Thats all you need to loose wieght without beefing up. I forgot to mention ‘patience’. Its key to any successful exercise regime. Dont go for the dryg/medicinal ‘short cuts’. There are no short cuts – just stay dedicated to your workout regime and enjoy it. You will see the results very soon :)
” No pain, no gain” – Arnold Schwarzenegger