Research has shown this is NOT an imaginary issue. As far back as 1975, researchers published a study in the journal Lancet that looked at the issue of weight loss resistance. 29 women who claimed they could not lose weight were studied. The researchers, like many of us, assumed these women simply were not compliant and wanted to test their metabolism by sequestering them in a house and controlling all food and exercise they did. Each woman was put on a strict 1500 calorie a day diet.

In autoimmune diseases, such as type 1 diabetes, the immune system mistakenly manufactures antibodies and inflammatory cells that are directed against and cause damage to patients' own body tissues. In persons with type 1 diabetes, the beta cells of the pancreas, which are responsible for insulin production, are attacked by the misdirected immune system. It is believed that the tendency to develop abnormal antibodies in type 1 diabetes is, in part, genetically inherited, though the details are not fully understood.
Cirrhosis of the liver refers to a disease in which normal liver cells are replaced by scar tissue caused by alcohol and viral hepatitis B and C. This disease leads to abnormalities in the liver's ability to handle toxins and blood flow, causing internal bleeding, kidney failure, mental confusion, coma, body fluid accumulation, and frequent infections.

At the end of the twelve-week study both groups lost weight, but the difference in the amount of muscle vs. fat loss was telling. The aerobic group lost 37 pounds over the course of the study. Ten of those pounds came from muscle. In contrast, the resistance-training group lost 32 pounds. None of the weight they lost came from muscle. When the resting metabolic rate of each group was calculated, the aerobic group was shown to be burning 210 fewer calories per day. The resistance-training group avoided this metabolic decline and instead was burning 63 more calories per day.

The previous definitions of the metabolic syndrome by the International Diabetes Federation[40] and the revised National Cholesterol Education Program are very similar and they identify individuals with a given set of symptoms as having metabolic syndrome. There are two differences, however: the IDF definition states that if body mass index (BMI) is greater than 30 kg/m2, central obesity can be assumed, and waist circumference does not need to be measured. However, this potentially excludes any subject without increased waist circumference if BMI is less than 30. Conversely, the NCEP definition indicates that metabolic syndrome can be diagnosed based on other criteria. Also, the IDF uses geography-specific cut points for waist circumference, while NCEP uses only one set of cut points for waist circumference regardless of geography. These two definitions are much more similar than the original NCEP and WHO definitions.

According to the Mayo Clinic, doctors may use other tests to diagnose diabetes. For example, they may conduct a fasting blood glucose test, which is a blood glucose test done after a night of fasting. While a fasting blood sugar level of less than 100 milligrams per deciliter (mg/dL) is normal, one that is between 100 to 125 mg/dL signals prediabetes, and a reading that reaches 126 mg/dL on two separate occasions means you have diabetes.
Type 2 diabetes, which is often diagnosed when a person has an A1C of at least 7 on two separate occasions, can lead to potentially serious issues, like neuropathy, or nerve damage; vision problems; an increased risk of heart disease; and other diabetes complications. A person’s A1C is the two- to three-month average of his or her blood sugar levels.
Metabolic syndrome is a cluster of metabolic risk factors that come together in a single individual. These metabolic factors include insulin resistance, hypertension (high blood pressure), cholesterol abnormalities, and an increased risk for blood clotting. Affected individuals are most often overweight or obese. An association between certain metabolic disorders and cardiovascular disease has been known since the 1940s.