Some find it easiest to go cold turkey. There are a couple of things to keep in mind. You may experience brain fog, low carb flu, or whatever you want to call it while transitioning. Some people don't get it, in some people it lasts a week or 3. Don't start low-carb if you have an important race or an exam coming up. Once you get past that point, most people experience more energy and clearer thought. The other issue is at the other end. Your body develops enzymes and gut flora to deal with the food you're used to. If you switch from high insoluble fibre to high soluble fibre, such as when you cut out grains and substitute veggies, some people experience constipation. Adding back some grains for a short time will usually clear that up.
Sugar alcohol is metabolized in the liver the same as alcohol or fructose. In some people it causes digestive issues, due to fermentation in the gut. The only benefit is that it doesn't promote tooth decay. Actually, all sugar substitutes should be avoided. The use of sugar substitutes has been linked to increases in obesity. It's better is to just avoid anything that tastes sweet than to use substitutes.http://www.innvista.com/health/nutritio ... lcohol.htm