Its a simple equation...... put less calories in than you need.

Depending on how much you need to loose in what time frame will depend on how you go about this.

You can obviously do it by diet alone, but you will need to be pretty strict. The other way is to do some exercise. People have mentioned doing cardio, but in all honesty if you have a good weights workout that lasts for 45-60mins you don't need to do much more cardio(unless you really need to shed loads of lbs).

I find cardio is more useful on a 'non-weight' day just to keep your body burning extra calories. But I am a bodybuilder and coz I'm not actively dieting I do zero cardio

If you want to add a bit of muscle and keep it, then make sure you DO eat after training. There is a 30-60min window after exercise where the body is more receptive to nutrients.

If you are really dedicated to loosing the weight, then first thing in the morning on an empty stomach is the best time to do low impact cardio, e.g go for a 20-30min walk at a pace where it is still comfortable to hold a conversation. This way you will not eat into your bodies muscle reserves.

People think that by starving themselves they will loose fat, but your body has an anabolic and catabolic state. If you starve yourself the body will stop using only fat as fuel and also burn up your muscles.

THe answer is small meals with a higher level of protein and lower level of carbs and fats. The protein will keep your body in an anabolic state and help it burn fat only.

I actually find cycling my carbs works well.

Day 1 Normal Carb day (basically i have potatos and pasta with meals)
Day 2 Reduced carb day (errrr no potatoes or pasta )
Day 3 Repeat low carbs

Then repeat. Anymore than 2 days on low carbs and I'm shattered in the gym.

Also have some carbs in the morning then leave them out of the lunch and evening meals. Although have a few after training for the reason further up. Use this window or your muscles will become depleted of glycogen/energy.

Hope this helps.