Over the years, there has been no shortage of devices that claim to help with what some call "problem areas" of their bodies. There have been roller contraptions for a flatter belly, gadgets to squeeze between flabby thighs, and even a weight you can shake to tone those soft arms.

In other words, consumers have been sold the notion that by training certain areas of their bodies more, they can lose the fat and flab in those areas. This idea is known as "spot reduction" or "targeted fat loss," and science says it's a myth.

Probably the most well-known study in this area was done by researchers at the University of Connecticut in 2007. They took a group of about 100 individuals and controlled their calorie intake and exercise. The participants in the study trained one arm only over the course of the project, which resulted in overall fat loss for the group. But there was no difference in fat measurements between the trained arm and the untrained arm.

In other words, fat loss due to reduced caloric intake and exercise was from all over the body and not any more dramatic in the targeted area.

Similar studies involving trained and untrained legs and tennis players with one dominant arm have yielded similar results.

Fat loss physiology.

Fat loss occurs when your body uses substances in fat cells for energy. Triglycerides in fat cells are broken down into simpler substances that enter the bloodstream. When exercising, your body draws these substances from all the body's fat cells, not just those around the area you are exercising.

So while all those sit-ups or crunches you're doing will likely build strength in your abdominal muscles, they are not aiding in fat loss from your abdominal area. The muscle you build might be instrumental in getting that six-pack you're after, but you'll have to uncover that muscle by losing the fat that's hiding it. And that fat loss will come from all over your body.

Where you accumulate fat may be in your genetics.

Have you heard anyone say something like: "If I eat that cupcake, it'll go straight to my hips?" Unfortunately, there might be more truth to that than there is to targeted fat loss.

That's because scientists also believe that where you first accumulate fat is largely a function of genetics. Men tend to pack on fat around their abdomen, while women tend to carry more fat around their hips and thighs. But this can vary depending on an individual's genetic makeup.

If you've seen an overweight person with a lean face, or someone with tree-trunk legs but a slim torso, you've seen these genetics at work. Not everyone carries fat the same way.

Overall fat loss is the path to a leaner body.

In accounting, there's a formula known as FILO -- "first in, last out." Think of a stack of papers on your desk that you have to get through. As that stack in your inbox grows, what gets put on top gets handled first and goes to the outbox first. The bottom of that stack, the first in, is going to be the last out.

Fat accumulation and fat loss typically work the same way. That cupcake goes straight to your hips because that's where you first store fat. As you continue to store fat, other areas are affected, too. And in most cases, the last pound you put on will be the first pound you lose. That cupcake and that pound on your hips will likely be the last to go.

A lot of this is probably contrary to what you've been led to believe. That's because there's money to be made in contraptions that are supposed to fix the parts of their bodies that make consumers most self-conscious.

There's no real money in the real truth. And the truth is that overall fat loss, not mythical spot reduction, is the path to a leaner body.

That's good news because you don't need any contraptions for overall fat loss—just proper nutrition and exercise.