If you don’t have an established exercise routine, simply walking is the best first step toward weight loss. “Walking is a pretty good entry point for people,” says Gagliardi. This is particularly true if you have been out of the gym for a while and want to ease back into a workout routine. One small study published in The Journal of Exercise Nutrition & Biochemistry found that obese women who did a walking program for 50 to 70 minutes three days per week for 12 weeks significantly slashed their visceral fat compared to a sedentary control group.
If you want to lose weight you should start by avoiding sugar and starch (like bread, pasta and potatoes). This is an old idea: For 150 years or more there have been a huge number of weight-loss diets based on eating fewer carbs. What’s new is that dozens of modern scientific studies have proven that, yes, low carb is the most effective way to lose weight.
The major reason HIIT works so well for dropping body fat is due to the greater calorie burn (or EPOC—excess post-exercise oxygen consumption) that's maintained after the workout is over. In other words, you burn more calories and more body fat while you're sitting around doing nothing. In addition to this increase in resting metabolism, HIIT is effective at enhancing the mechanisms in muscle cells that promote fat burning and blunt fat storage.
You’ll start each cardio day with Tabata-timed cardio. The HIIT protocol that follows calls for sprinting “on the minute,” meaning that your sprints and active rest will always add up to a minute. You’re free to choose your method of cardio, but treadmill running has been shown to burn more calories than cycling. In the first workout, perform 10 all-out 12-second sprints, with 48 seconds of active rest. This will amount to 120 seconds of total sprinting. The next time out, do more: 11 sprints at 13 seconds each, with active rest diminishing by a second. You can expect a similar uptick in volume each cardio session.
Although you do want to increase your walking over time, this doesn’t necessarily mean that you have to be working your way up to a more intensive form of cardio like swimming or running. “Moving on to new exercises is not something someone should feel they have to do unless their goals change and a new exercise is needed to support those goals,” says Gagliardi. “Walking alone can be progressed by changing the distance, speed, terrain, and by adding intervals.”
In a way, moderate-intensity physical activity is that "magic pill" a lot of people are looking for, because the health benefits go beyond keeping your waistline trim: Not only can it reduce your risk of cancer, stroke, diabetes and heart attacks, but studies have shown that physical activity can significantly improve the moods of patients with major depressive disorders.