The next stage from overweight and obesity, before diabetes, is the metabolic syndrome. The obesity epidemic has significantly increased the prevalence of metabolic syndrome.
Metabolic syndrome has been called many other names:
Syndrome X
Insulin Resistance Syndrome
Deadly Quartet
Definitions:
Metabolic syndrome is cluster of metabolic abnormalities and cardiovascular risk factors. The outcome of this cluster is cardiovascular diseases and diabetes.
Several agencies have defined metabolic syndrome:
National Cholesterol Education Program Adult Treatment Panel III
World Health Organization
American Association of Clinical Endocrinologists
European Group for the Study of Insulin Resistance
Despite the different definitions from different agencies, they all agree on the foundation abnormalities.
Glucose intolerance
Obesity
Hypertension
Hyperlipidemia
National Cholesterol Education Program Adult Treatment Panel III
Three of the the following five criteria:
Abdominal obesity (waist circumference)
Men >102 cm (>40 in)
Women >88 cm (>35 in)
Triglycerides >150 mg/dL
HDL Cholesterol
Men <40 mg/dL
Women <50 mg/dL
Blood Pressure >130/>85 mm Hg
Fasting Glucose >110 mg/dL
World Health Organization
Insulin resistance, identified by one of the following:
if fasting glucose is <110 mg/dL, glucose uptake is below the lowest quartile for the appropriate population in hyperinsulinemic, euglycemic conditions
Plus any two of the following:
Antihypertensive medication and/or high blood pressure
>140 systolic or >90 diastolic
Plasma triglycerides >150 mg/dL
HDL cholesterol
men <35 mg/dL
women <39 mg/dL
BMI >30 kg/m2 or waist:hip ratio
men >0.90
women >0.85
Urinary albumin excretion rate >20 microg/min or albumin:creatinine ratio >30 mg/g
American Association of Clinical Endocrinologists
The diagnosis depends on the clinical judgment of these risk factors:
Overweight or Obesity
BMI >25 kg/m2
Triglycerides >150 mg/dL
HDL
men <40 mg/dL
women <50 mg/dL
Blood Pressure >130/85 mm Hg
Fasting Glucose >140 mg/dL
Other risk factors
Family Hx
type 2 diabetes
hypertension
coronary artery disease
Polycystic ovary syndrome
Sedentary lifestyle
Advancing age
Ethnic groups with high risk of type 2 diabetes
European Group for the Study of Insulin Resistance
Insulin resistance - hyperinsulinemia in top 25% of fasting values from a non-diabetic population
Plus two or more of the following:
Central Obesity (waist circumference)
men >94 cm
women >80 cm
Dyslipidemia
Triglycerides >2.0 mM/L
or
HDL <1.0 mM/L
Hypertension
>140/90 mm Hg
and/or
antihypertensive medications
Fasting glucose >6 mM/L
One day there may be a single set of criteria to define metabolic syndrome. Currently, metabolic syndrome is not considered a diagnosis. Nor is there any recongnized treatment, except treating each individual risk factor.
Glucose tolerance is determined by fasting blood glucose and a glucose tolerance test. For the Oral Glucose Tolerance Test, a glucose rich fluid (1.75 g/kg) is consumed in the fasting state. Blood glucose is measured before and every 30 minutes after drinking the glucose rich fluid.
Glucose Tolerance/Intolerance
Baseline
Two Hour
Normal Response (mg/dL)
<110
<140
Impaired Fasting Glucose
<110 & >125
<140
Impaired Glucose Tolerance
>126
>140
Because there are so many definitions of metabolic syndrome it is difficult to determine the prevalence in a population. The National Cholesterol Education Program Adult Treatment Panel III criteria is used in the US. It is estimated that over 50% of women and 40% of men exhibit metabolic syndrome. The US has the highest prevalence, with Iran and Turkey following closely behind.
Etiology
The etiology of metabolic syndrome is not that different from the etiology of overweight and obesity. The common characteristic of obesity and metabolic syndrome is the visceral fat deposit and insulin resistance. It also is probably this link that separates metabolic syndrome from overweight and obesity. All overweight and obese individuals do not necessarily exhibit upper body fat distribution and/or insulin resistance. The question then becomes, what causes the upper body fat distribution vs. normal fat distribution?
We already know that weight cycling contributes to upper body fat deposits. However, the most contributing factor may be genetics.
For the role of insulin in carbohydrate metabolism, visit our page on diabetes. Insulin resistance in the absence of diabetes is exhibited in metabolic syndrome. Insulin resistance is the condition in which normal amounts of insulin are inadequate to produce a normal insulin response in adipose, muscle and liver cells. Insulin resistance can also be called insulin (in)sensitivity. Insulin resistance is diagnosed with a glucose tolerance test.
Pathophysiology
What is the link among visceral adipose deposits, hypertension, hyperlipidemia and insulin resistance?
Exercise Effectiveness
Since the etiology and pathophysiology of metabolic syndrome are similar to overweight and obesity, the effectiveness of exercise in the prevention and treatment should be similar.
On an epidemiologic level, there is a lowered risk for all-cause mortality in fit adults with metabolic syndrome. This study observed the risk in 19,223 men; 3757 exhibiting metabolic syndrome. Fitness was measured by Blair at the Cooper Clinic.
Similarly, there is a negative relationship between the amount of vigorous physical activity (measured by questionnaire) and incidence of metabolic syndrom.
Rennie, Kl.L., N. Mc Carthy, S. Yazdgerdi, M. Marmot, and E. Brunner. Association of metabolic syndrome with both vigorous and moderate physical activity. International Journal of Epidemiology 32:600-606, 2003.
In terms of training: As part of the HERITAGE Family Study, the team found 105 subjects who exhibited metabolic syndrome based on three or more risk factors identified by the National Cholesterol Education Program Adult Treatment Panel III.
Subjects began exercising for 30 min, supervised on a cycle ergometer @ 55%, 3/wk progressing to 50 min at 75% over a 20 week period.
The figure to the right illustrates what percent of the 105 subjects exhibited elevated variables at baseline (blue). The reduction in these variables is illustrated by the red bars.
Exercise was effective in eliminating metabolic syndrome in 32% of the subjects.
In the treatment of metabolic syndrome, excess body fat is the target for exercise treatment. That is, the exercise recommendations for overweight and obesity apply to metabolic syndrome.
Reduced-energy diets, consisting of a modest 500- to 1000-calorie/day reduction
Reduce body weight by 7% to 10% over a period of 6 to 12 months
