The ultimate goal of exercise, for most people, is to lose weight. Losing weight, however, needs to involve fat loss, and not just general weight loss. Your ultimate goal should be to lose fat and build/retain muscle.
Method
For most people, cardio is an absolutely necessary component of weight loss, and beginners should always start with a basic cardio regimen. Not all cardio is as conducive to weight loss as others, though, and there are a few things that you should keep in mind.
First of all, different intensities will produce different results, as far as fat loss is concerned. Most people, however, respond well to lower-intensity cardio that is performed over a moderate-to-lengthy duration, such as 30 minutes on an elliptical set at a medium elevation. This encourages your body to expend energy through the oxidative system, which uses fat and carbohydrates as substrates.[1] This means that your body is using fats and carbohydrates as fuel for the exercise, rather than burning away your hard-earned muscle.
Beginning routine
Although you may need to make some adjustments in the future, all beginners should start with a routine that involves 4-5 sessions of cardiovascular training for durations of about 30 minutes each time.
Relative to fat loss, though, it is most beneficial to perform your cardiovascular training at periods of the day when your blood sugar is low, such as after you wake up and before breakfast, or after a weight-training session.
Diet
While cardio is a huge part of fat loss, diet is even more important. Without a proper diet, you will never see adequate results.
Generally speaking, you need to create a caloric deficit in your body in order to lose fat. This would mean that if your body needs 2500 calories a day to function at rest, then you need to eat less than 2500 calories in order for your body composition to change.
It is also important to monitor your macronutrients, which are your protein and carbs. The general rule is to eat about 1g of protein per pound of bodyweight each day, and to limit your carbohydrate intake. This does not mean following an Atkins-type, ketogenic diet; it simply involves monitoring the amount of carbs you take in, because carbohydrates that are not used are stored as fat. An example would be eating approximately 1.5g of carbs per pound of bodyweight each day.
