I am not a doctor / lawyer / psychic, so take what I say with a big grain of salt...
Every diet has risks, Atkin's biggest is it is very hard on your kidneys, particularily in the first month. You absolutely must drink lots of water. They recommend at least 64 ounces. Also, you absolutely must spread it out over the whole day, not all at once.
Atkins also requires a certain amount of fat intake per day, especially at the beginning. This can be dangerous to people with heart conditions.
Other than that, it must be followed very closely, especially the first month. As with any diet, exercise is an important component of the diet; without making at least a minimal effort to do some physical activity any weight loss will be marginal at best.
Keep in mind the long term goal of the diet isn't weight loss, it is healthy eating, which is a topic most diets fail to stress. Many people fail because they lose weight, think they are done, then stop eating appropriately. Atkin's big points are that weight is gained from excessive Carbohydrates. While some carbs are ok, most food we eat these days is so loaded with sugars, starches, and processed grains that cause an average person to eat thousands of unnecessary carbs a day. By cutting out carbs almost entirely, then slowly reintroducing natural carbs, you'll develop a balance while eating more healthy foods.
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