Another option is to decrease the intake of carbohydrates slowly, over a few weeks, to minimize side effects. But the “Nike way” (Just Do It) may be the best choice for most people. Removing most sugar and starch often results in several pounds lost on the scale within a few days. This may be mostly fluids, but it can still be great for motivation.
Now if you're thinking you'll just handle the problem by brushing and flossing a little more often, guess again. Since the breath odor is coming from metabolic changes and not necessarily a dental-related condition, traditional breath products are not likely to provide long-lasting relief. On the other hand drinking more water intake can do the trick.
There is a reason why we store hundreds of thousands of calories in the form of fat in our body and only about 2000 calories in the form of glucose (with only a small amount of this useable by the brain). The reason is simple - The body prefers fat as its fuel source. Mark Sisson explains this in his article ‘A metabolic Paradigm Shift, or Why Fat is the Preferred Fuel for Human Consumption’.

The studies done on ketosis and endurance sports performance paint a pretty clear picture – it helps.  One of the most detailed studies on fat utilisation and performance (compared to a standard carb diet) was named the FASTER study - the results found that those who were on a ketogenic type diet had more mitochondria than the control group, lower oxidative stress, lower lactate load and that the fat adapted and fuelled athletes could function off fat for a much higher intensity than the non-fat adapted counter parts.