Fitness and weight loss is not just about spending time at the gym and eliminating certain foods from your diet; your mental state can have a huge influence on whether you can hit your weight loss goals. Cortisol the stress hormone slows down your body's metabolism. So if you stay stressed for a long time your body will not be able to burn as many calories as it should. So beat stress with this fitness regime. Diet plan Morning: Start your day with a glass lauki juice. Lauki is excellent to boost your energy levels and kick start your day.