Some risks of the keto diet include low blood sugar, negative medication interactions, and nutrient deficiencies. (People who should avoid the keto diet include those with kidney damage or disease, women who are pregnant or breast-feeding, and those with or at a heightened risk for heart disease due to high blood pressure, high cholesterol, or family history. (40)
At the end of the 3 week period most of the women ended up losing weight. However, 10 women did not lose any weight, and 1 of the women actually gained weight. This makes two points very clear. First, metabolism varies from person to person. Second, compensatory reactions can suppress the metabolism so much that even very low calorie diets are no longer effective even in the short-term.
A positive result, in the absence of unequivocal high blood sugar, should be confirmed by a repeat of any of the above methods on a different day. It is preferable to measure a fasting glucose level because of the ease of measurement and the considerable time commitment of formal glucose tolerance testing, which takes two hours to complete and offers no prognostic advantage over the fasting test.[66] According to the current definition, two fasting glucose measurements above 7.0 mmol/l (126 mg/dl) is considered diagnostic for diabetes mellitus.
Exogenous administration of the other steroids used for therapeutic purposes also increases blood pressure (BP), especially in susceptible individuals, mainly by volume expansion. Nonsteroidal anti-inflammatory drugs (NSAIDs) may also have adverse effects on BP. NSAIDs block both cyclooxygenase-1 (COX-1) and COX-2 enzymes. The inhibition of COX-2 can inhibit its natriuretic effect, which, in turn, increases sodium retention. NSAIDs also inhibit the vasodilating effects of prostaglandins and the production of vasoconstricting factors—namely, endothelin-1. These effects can contribute to the induction of hypertension in a normotensive or controlled hypertensive patient.
But why does someone get to this point?  For the chronic dieter they arrive with metabolic damage because they hold tightly to the “Eat less, exercise more” mantras they were taught.  When weight loss slows down, they eat less and push harder in their exercise routine, pushing metabolism into the ground.  For the person with the unknown metabolism problem their road to metabolic damage is much more subtle.  This person simply isn’t feeling well, starts putting on weight, and progresses all the way to metabolic damage because no doctor was able to identify what was going wrong.
According to the Centers for Disease Control and Prevention, more than 50% of people age 50 and older have high blood pressure. Women are about as likely as men to develop high blood pressure, though this varies somewhat by age. For people younger than age 45, more men than women are affected, while for those age 65 and older, more women than men are affected. Americans of African descent develop high blood pressure more often and at an earlier age than those of European and Hispanic descent.
Cataracts and glaucoma are also more common among diabetics. It is also important to note that since the lens of the eye lets water through, if blood sugar concentrations vary a lot, the lens of the eye will shrink and swell with fluid accordingly. As a result, blurry vision is very common in poorly controlled diabetes. Patients are usually discouraged from getting a new eyeglass prescription until their blood sugar is controlled. This allows for a more accurate assessment of what kind of glasses prescription is required.