This is a difficult question to answer because of a number of factors. Everyone’s body reacts differently to different stimuli – exercise and food included – so it makes it difficult to give a short answer.
Typically, a diet of natural foods (stay away from packaged and processed foods) combined with exercise will help people lose weight. Timing and portioning your meals can also help. Try to eat several smaller meals throughout the day instead of 3 big meals. The overall amount of food will be the same but your body is better able to digest it over the day in spaced out intervals. As for exercise, a routine that combines resistance training (weight lifting) and high intensity cardio (burpees, sprinting, etc.) will rev up your metabolism. The resistance training will create more muscle which will raise your metabolism and overall energy (calorie use) expenditure all day long and even at rest while the high intensity cardio only needs to be done for a short period of time to burn even more calories.
Both. To rid yourself of unwanted abdominal fat you need to reduce your overall food intake (only a small amount if you exercise intensely) and exercise.
Resistance training (weight lifting) can help by building more muscle in your body which in turn raises your metabolism and burns more calories – while you rest and work. High Intensity Cardio training has been proven in studies to be more effective in weight loss than Stead State Cardio (jogging, walking, etc.) because of the amount of oxygen your body expends during these intense bouts. Your muscles become depleted of their oxygen stores, and enter a condition known as EPOC (excessive post exercise consumption). In this state, your body continues to expend calories as it replenishes your muscles with oxygen and nutrients, effectively burning calories for hours AFTER you finish exercising!
Machines follow a precise range of motion for a specific muscle and help prevent injury because the weight is controlled throughout its movement. Because of this, machines are used in injury rehabilitation, by beginners in resistance training and by experienced lifters looking to isolate a particular muscle (usually pre competition). Weight Machines do not however, simulate real lifting conditions. Very little balance is involved by the lifter and the smaller stabilizing muscles do not get used. Free weights on the other hand have infinitely variable ranges of motion and can significantly affect balance and other muscles beside the ones being targeted. This is good for building muscle, balance and coordination but can also lead to injury if not done properly.