Over 8–10 mmol/l: It’s normally impossible to get to this level just by eating a keto diet. It means that something is wrong. The most common cause by far is type 1 diabetes, with a severe lack of insulin. Symptoms include feeling very sick with nausea, vomiting, abdominal pain and confusion. The possible end result, ketoacidosis, may be fatal and requires immediate medical care.
These findings were backed up in a 2012 study which had obese diabetics follow a ketogenic diet for 12 months. The researchers found lower fasting glucose levels, improved cholesterol markers and improved HA1c readings. Remember, carbs and glucose are not required when on a ketogenic diet, as stable, clean burning energy is sourced from fat. This makes controlling blood sugar levels near foolproof.
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.
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.