Muscles exert higher EMG tension when they are contracting eccentrically (lowering the resistance) versus raising it; but the problem with most exercises is that the amount of weight you can lower is limited by how much you can lift positively (concentric work). This exercise compensates for the problem by changing the leverage during the lowering (eccentric) phase of the exercise.
Core exercises target the same muscles that crunches do — but they also include your hip and lower-back muscles. So what's a true core exercise? One that trains you to keep your spine stable and in its natural alignment. Besides the plank (more on that in a minute), scores of exercises qualify, including the side plank, mountain climber, rollouts, hollow body holds, and even the pushup.
In regards to weight training, use mainly compound exercises in your routine. Compound exercises involve movement at more than one joint and involve mainly major muscle groups. Bench press, squats, and dumbbell rows are all examples of compound exercises. These types of exercises stimulate more muscle fibers than isolation exercises and are more metabolically demanding.
Despite the fact that sit-ups been widely rebuked—everyone from Harvard Medical School to the U.S. Army advises against performing them—you shouldn’t discount the classic move just yet. The sit-up’s “primary function is to work your rectus abdominis, which are those six-pack muscles that most people want,” says Katie Barrett, lead instructor at B/SPOKE Cycling Studio in Boston and a certified personal trainer. “But doing that full sit-up is also going to work your hip flexors and other stabilizing core muscles.” The key is making sure you’re doing them correctly. (And here’s how to do just that).
Eat carbs. "There's this notion that carbs are bad and that you need crazy amounts of protein to be lean and fit," says Alcantara, who disagrees, and eats just as much carbs as protein, although the ideal ratio varies based on your goals. "Whatever you eat to get the results you want has to be sustainable, otherwise you're going to end up right back where you started with the same habits that got you there."