No one can diet for long and keep losing weight without exercising as well. What you do to burn calories is up to you; however, I highly advocate at least a three day per week weight lifting regimen in addition to your regular cardio. I recommend this for two reasons: muscle burns energy more efficiently than fatty tissue, and weight training strengthens bones and connective tissue--vital for longevity and long-term health. Adding some muscle to your frame will definitely help you look more toned as well. BUT the body is a SYSTEMIC organism—spot reduction, i.e. burning fat off a particular area by training the muscles in that area DOES NOT WORK! You can build muscle in a certain area and the muscles will push through the fat layer more, creating the look of more definition, but the fat will remain the same unless you lose it systemically.
Glycogen is your body’s main source of quick, easily accessible energy. Glycogen is soluble carbohydrates stored in your liver and in your muscle tissue. Glycogen must be depleted in order for your fat stores to be next in line as an energy source. Liver glycogen is depleted after a long fasting period, such as a good night’s sleep. This is why cardio is most effective first thing in the morning before breakfast--I also find that cardio is just plain easier to do early in the morning. Cardio can be as easy as a 30 minute brisk walk or as intense as an hour trail run; I recommend keeping your heart rate at about 60-70% of your max, for healthy adults this means around 120-130 beats per minute. If you choose not to do your cardio first thing in the morning, keep in mind that the first 20-30 minutes of your session will be spent depleting liver and muscle glycogen rather than burning fat--meaning additional cardio is necessary. Cardio after weightlifting is also fairly effective because weightlifting will deplete both stores of glycogen somewhat, allowing you to burn bodyfat more readily.
When it comes to losing body weight, it is extremely important to be consistent in your tracking methods. This means always weighing yourself at the same time (the best time is before your morning cardio, after using the restroom and before breakfast--basically an entirely empty stomach), in the same or similar clothing and on the same scale. Start doing this on a daily basis; tracking your losses will help you to determine whether or not your diet is working in its current form.
Starting a diet and exercise log right away will also help you stay on track and determine how well your diet is working. As your diet becomes more and more difficult (which it will if you want to keep losing bodyfat), the urge to stray outside your diet parameters will become stronger and stronger, and diet logs are a great way to head off these cravings. Diet and exercise journals can be a simple spiral bound notepad or a carefully designed web journal with personalized calorie trackers. Nutridiary and Fitday are both good online options. When cataloging what you are eating, honesty is as important as ever. Sometimes being held accountable to another person for your diet will help you stay on the straight and narrow when things get rough. For others, simply putting what they have eaten down on paper is enough to discourage excessive eating or poor food choices. Think of how embarrassing it would be to admit to your diet or training partner that you had chocolate cake instead of chicken salad for lunch!
“Nothing tastes as good as skinny feels,” Heidi Klum says. Anyone who has ever enjoyed their food knows that this statement is false. So what do we do about all these cravings? While keeping a diet log can help head off unplanned deviations from your diet, it is a good idea to allow yourself one weekly meal during which you may eat anything you desire. It is important that this “meal” does NOT stretch into a day-long free-for-all. One single meal will satisfy your cravings and give you something to look forward to during the week, but not put you too much off track. It is a good idea to allow yourself this “cheat meal” on the same day every week, and only if you have achieved your goal for that week.
Hope this helps!