Over the years, numerous routines and techniques have been promoted as a way to make your ab workouts more effective. However, very few of these methods have any real scientific foundation. Some may even be harmful.

Are your ab workouts doing more harm than good?

When it comes to ab training, you hear it all: Doing sit-ups with bent rather than straight legs takes the stress off your back and works your abs harder; the bicycle maneuver and the captain's chair are the "best" exercises for your abs; the hanging leg raise puts little or no stress on your lower back.

Unfortunately, conventional wisdom and the word in the gym isn't always accurate. Sometimes it's dangerous.

Abdominal exercises are usually recommended based on their capacity to work your abdominal muscles. However, this ignores the potential tissue damage that some exercises can cause, mainly through compressive loading to the lumbar spine (lower back).

In other words, while some exercises may be effective at working your abs, they're actually very bad for your back.

Meal Plan #1 (1510 calories)

The right training program provides the trigger for muscle growth. However, the real key to gaining muscle lies in getting your diet right. If you don't provide your body with the raw material it needs to grow, then you simply won't make the progress you deserve — no matter how hard or how often you train.

Here's how to design your own muscle-building nutrition plan...

With the mass of conflicting opinions, weight gain supplements, and "secret" training programs, it's no wonder so many people are confused about how to gain weight.

Unfortunately, even when people get their hands on the right information about how to gain weight, very few use it. Instead, they go out and search for even more information!

Rather than help people gain weight, this conflicting information often confuses them to the point of despair. They feel like throwing up their arms in frustration at the fact that "even the experts can't agree."

For those wanting to the facts about how to gain weight, the real problem isn't too little information but too much. With one clock, you always know what the time is. With two clocks, you're never sure!

This two-part series will put an end to that confusion. You'll discover how to gain weight without relying on "old school" bulking plans that leave you with more fat than muscle. And you won't need to waste a fortune on supplements or spend hours in the kitchen cooking and preparing food.

Imagine never having to worry about what you eat. Imagine being one of those people who seem able to eat whatever they want whenever they want and never gain a pound — even lose weight! Don't you hate those people? What if you could be just like them? What if you knew their secret (that even they probably don't know)?

This nutrition plan is based on the principles outlined in The Anatomy of a Balanced Diet. Firstly, protein intake is set at a level that's adequate to preserve muscle. To ensure you're getting enough of the essential fats, around 20-30% of the total calories come from fat. Carbohydrate intake is then adjusted according to how active you are.

The idea that grapefruit promotes weight loss is not news. But, until recently, there were no studies to support this claim. That all changed when researchers at Scripps Clinic of San Diego decided to study the grapefruit diet.

"For years people have talked about the grapefruit diet, and some even swear by it, but now, we have data that grapefruit helps weight loss," says Dr. Ken Fujioka, a researcher at Scripps Clinic.

Does this latest study mean that advocates of the grapefruit diet were right all along?

Let's take a closer look.

Scientists for Cancer Research UK compared the weight gains of 22,000 meat eaters, fish eaters, vegetarians and vegans over a five-year period.

On average people gained two kilograms but those who had switched to a diet with less animal foods gained a little less.

The prevalence of obesity has reached epidemic proportions and many Americans are making efforts to side-step extra calories. They are turning to diet soft drinks — Diet Coke, Pepsi, Dr. Pepper and Sprite — as their beverage of choice.

But is this a wise health choice?