Sure, they are said to be effective in losing weight easy and fast, which is exactly what most of us dream of.

But hey, a report in the Archives of Internal Medicine pointed out that low-carbohydrate, high protein diets are found to increase our cholesterol levels. And we are referring to both LDL (low density lipoprotein, which is also known as "bad" cholesterol) and HDL (high density lipoprotein which is also the "good" cholesterol).

HDL helps the body get rid of bad cholesterol. LDL is said to cause build-up of plague on the artery walls, contributing to risks of cardiovascular diseases.

The findings were from an analysis of the five clinical trials comparing low-fat diets with low-carbohydrate diets. A total of 447 volunteers ranging from 42 to 49 years old took part in these trials. Out of 447 participants, 225 are on low-fat diets while the rest are on low-carbo diets.

Both groups were then tested for their weight loss and blood pressure after six and nine months' period. It was expected that for the first 6 months, the participants on the low-carbo diet had lost more weight. After 12 months, the outcome of weight loss and blood pressure turned out to be the same for both groups.

What raises our concern was that from the results of low-carbo diet group, total cholesterol increased throughout the 12 months period. It was agreed that a low-carbo diet is often high in fat, which inevitably increases cholesterol levels.

However, the results further show that a higher cholesterol level had led to a concurrent increase in both LDL and HDL. They also had a lower level of triglycerides, a type of fat, which LDL carries in the blood.

So does the beneficial effects of low-carbo diet appear to have on HDL and triglyceride levels cancel out their apparent negative effects on overall and LDL cholesterol levels?

Not necessarily so, as another study published in the Journal of Lipid Research in 2003 showed that high triglyceride levels, high LDL levels and low HDL levels are actually independent risk factors for cardiovascular disease.

So despite what the low-carbo diet results show, more evidence is needed to support the conclusion as the study had its limits. The researchers in the low-carbo diet report also expressed concern about the effects of the low-carbo diet on cholesterol levels and the cardiovascular system as it contains large amounts of fats and proteins.

This is because you are more likely to consume more foods high in saturated fats when you turned to high-protein diet. This increases your calories as fat provides more calories per gram than carbohydrates. Fat contains nine calories per gram while carbohydrates provide four calories per gram.

As you consume more fats, you are exposing yourself to higher risk of developing coronary heart disease.

A high-protein diet also said to cause other health problems including kidney failure, high cholesterol levels, osteoporosis and kidney stones. As a guide, an adult should obtain 50 to 60 percent of their calories from carbohydrates, 10 to 15 percent from protein and 20 to 30 percent from fats.

Therefore, it is not advisable to go long term on low-carbo, high-protein diets.