Originally Answered: Atkins diet?
The Atkins is one of the healthiest, most effective diets you can go on. But, remember that a low carb diet should be a life-long habit.
When I first heard about the diet about 8 years ago, I was very skeptical, so I did a lot of reading and research. I was also in the Army Reserve at the time and they calculated my body fat percentage once a month. Lastly, and very importantly, I was the director of a hospital laboratory, so I could monitor my blood and urine values.
I was amazed at how well I felt once I crossed over into ketosis. I had so much more energy and felt much more alert. I rarely felt hungry because my blood sugar stayed rock steady at around 100-105 mg/dl whether I was fasting or not. I ate at least 2000 calories a day. My hemoglobin went up and all of my chemistries improved, especially my cholesterol and triglycerides. I lost about 30 pounds within about 5 months and all of it was fat - I lost absolutely no muscle mass.
A side benefit of this diet is that it will stop the progression of diabetes type II. My mother and my two brothers are diabetic and they've been able to get their blood sugar under control by restricting their carbs.
Once you lose the desired fat, you can slowly increase your daily carb intake, but remember that a low carb diet should be lifelong. The maintenance diet is very healthy and emphasizes plenty of vegetables, protein foods, moderate amounts of fat, limited fruits, and very few starchy foods. Keep the sugar out of your diet.
I do recommend, before you start this diet, you thoroughly read "Protein Power" as well as the Atkins book so that you thoroughly understand why this eating plan works so well and why it is so important to control your blood sugar and insulin levels.
By the way, in my research I was unable to find a single legitimate "negative" about the diet, nor was I able to demonstrate any negatives while monitoring my own lab values.