It is common for there to be a development of visceral fat, after which the adipocytes (fat cells) of the visceral fat increase plasma levels of TNF-α and alter levels of a number of other substances (e.g., adiponectin, resistin, and PAI-1). TNF-α has been shown not only to cause the production of inflammatory cytokines, but also possibly to trigger cell signaling by interaction with a TNF-α receptor that may lead to insulin resistance. An experiment with rats fed a diet with 33% sucrose has been proposed as a model for the development of metabolic syndrome. The sucrose first elevated blood levels of triglycerides, which induced visceral fat and ultimately resulted in insulin resistance. The progression from visceral fat to increased TNF-α to insulin resistance has some parallels to human development of metabolic syndrome. The increase in adipose tissue also increases the number of immune cells present within, which play a role in inflammation. Chronic inflammation contributes to an increased risk of hypertension, atherosclerosis and diabetes.
In 1977 and 1978, Gerald B. Phillips developed the concept that risk factors for myocardial infarction concur to form a "constellation of abnormalities" (i.e., glucose intolerance, hyperinsulinemia, hypercholesterolemia, hypertriglyceridemia, and hypertension) associated not only with heart disease, but also with aging, obesity and other clinical states. He suggested there must be an underlying linking factor, the identification of which could lead to the prevention of cardiovascular disease; he hypothesized that this factor was sex hormones.
The primary problem in metabolic syndrome is insulin resistance. In the body's attempt to compensate for insulin resistance, extra insulin is produced, leading to elevated insulin levels. The elevated insulin levels can lead, directly or indirectly, to the characteristic metabolic abnormalities seen in these patients. Frequently, the insulin resistance will progress to overt type 2 diabetes, which further increases the risk of cardiovascular complications.
The key sign of metabolic syndrome is central obesity, also known as visceral, male-pattern or apple-shaped adiposity. It is characterized by adipose tissue accumulation predominantly around the waist and trunk. Other signs of metabolic syndrome include high blood pressure, decreased fasting serum HDL cholesterol, elevated fasting serum triglyceride level, impaired fasting glucose, insulin resistance, or prediabetes. Associated conditions include hyperuricemia; fatty liver (especially in concurrent obesity) progressing to nonalcoholic fatty liver disease; polycystic ovarian syndrome in women and erectile dysfunction in men; and acanthosis nigricans.
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.
Metabolic syndrome is a multiplex risk factor that arises from insulin resistance accompanying abnormal adipose deposition and function.  It is a risk factor for coronary heart disease, as well as diabetes, fatty liver, and several cancers. The clinical manifestations of this syndrome may include hypertension, hyperglycemia, hypertriglyceridemia, reduced high-density lipoprotein cholesterol (HDL-C), and abdominal obesity. (See Prognosis, Workup, Treatment, and Medication.)
American Diabetes Association Joslin Diabetes Center Mayo Clinic International Diabetes Federation Canadian Diabetes Association National Institute of Diabetes and Digestive and Kidney Diseases Diabetes Daily American Heart Association Diabetes Forecast Diabetic Living American Association of Clinical Endocrinologists European Association for the Study of Diabetes
Researchers assigned overweight subjects to three groups: diet-only, diet plus aerobics, diet plus aerobics plus weights. The diet group lost 14.6 pounds of fat in 12 weeks. The aerobic group lost only one more pound than the diet group. Their training was three times a week starting at 30 minutes and progressing to 50 minutes over the 12 weeks. Nothing special. But the weight training group lost over 21 pounds of fat. That's 44% and 35% more than diet and cardio-only groups respectively. The addition of aerobic training didn't result in significant fat loss over dieting alone. Thirty-six sessions of up to 50 minutes is a lot of work for one additional pound of fat loss. But the addition of resistance training greatly accelerated fat loss results.
Hypertension is diagnosed on the basis of a persistently high resting blood pressure. The American Heart Association recommends at least three resting measurements on at least two separate health care visits. The UK National Institute for Health and Care Excellence recommends ambulatory blood pressure monitoring to confirm the diagnosis of hypertension if a clinic blood pressure is 140/90 mmHg or higher.
Cortisol reactivity, an index of hypothalamic-pituitary-adrenal function, may be another mechanism by which psychosocial stress is associated with future hypertension.  In a prospective sub-study of the Whitehall II cohort, with 3 years follow-up of an occupational cohort in previously healthy patients, investigators reported 15.9% of the patient sample developed hypertension in response to laboratory-induced mental stressors and found an association between cortisol stress reactivity and incident hypertension. 
Enlarged heart. High blood pressure increases the amount of work for your heart. Like any heavily exercised muscle in your body, your heart grows bigger (enlarges) to handle the extra workload. The bigger your heart is, the more it demands oxygen-rich blood but the less able it is to maintain proper blood flow. As a result, you feel weak and tired and are not able to exercise or perform physical activities. Without treatment, your heart failure will only get worse.
In a meta-analysis of pooled data from 19 prospective cohort studies involving 762,393 patients, Huang et al reported that, after adjustment for multiple cardiovascular risk factors, prehypertension was associated with a 66% increased risk for stroke, compared with an optimal blood pressure (< 120/80 mm Hg). [41, 42] Patients in the high range of prehypertension (130-139/85-89 mm Hg) had a 95% increased risk of stroke, compared with a 44% increased risk for those in the low range of prehypertension (120-129/80-84 mm Hg). [41, 42]
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.