Obesity & Metabolic Syndrome

NIDDK: "Obesity is a chronic disease that affects more than 4 in 10 adults in the United States, and nearly 1 in 10 Americans have severe obesity." "People who have a BMI between 25 and 30 are considered to be overweight. Obesity is defined as having a BMI of 30 or greater."

Classes (USPSTF). BMI is "calculated as weight in kilograms divided by height in meters squared." "The USPSTF uses the following terms to define categories of increased BMI: “overweight” is a BMI of 25 to 29.9 and “obesity” is a BMI of 30 or higher. Obesity can be categorized as class 1 (BMI of 30.0 to 34.9), class 2 (BMI of 35.0 to 39.9), or class 3 (BMI of ≥40)."

Where the fat is matters. NIDDK: "Overweight and obesity may increase your risk for many health problems—especially if you carry extra fat around your waist."

Weight bias. NIDDK: "Studies show that people with overweight or obesity are also likely to face weight-related bias at school and work, which may cause long-term harm to their quality of life." This page uses person-first wording — "people with obesity."

StatPearls: "Central obesity is the primary component of metabolic syndrome, leading to insulin resistance, hypertension, and dyslipidemia." "Visceral obesity has been identified as the main trigger of all pathways involved in the pathogenesis of metabolic syndrome, and high-calorie intake is the primary cause of visceral fat accumulation."

Insulin resistance. "Under normal circumstances, a sudden rise in serum glucose level triggers insulin secretion from the pancreatic β-cells, which promote cellular glucose uptake via glucose transporters. However, in those with insulin resistance, tissues are less sensitive to this acute rise in insulin, resulting in a higher serum glucose level and hyperinsulinemia" (StatPearls).

Free fatty acids. "Free fatty acids released by the adipose tissues promote insulin resistance and inhibit insulin secretion from the pancreatic beta cells." "The high-free fatty acids inhibit glucose uptake in skeletal muscles and increase hepatic gluconeogenesis and lipid synthesis by inducing protein kinases" (StatPearls).

Inflammation and clotting. Visceral fat secretes "various pro-inflammatory cytokines, C-reactive protein, leptin, and resistin, which induce chronic inflammation." "Insulin resistance further activates inflammatory cytokines and promotes thrombogenesis by increasing the fibrinogen level" (StatPearls).

Vessels. "Insulin resistance causes microvascular damage, predisposing patients to endothelial dysfunction, vascular resistance, hypertension, and vessel wall inflammation." "Dyslipidemia associated with metabolic syndrome can drive the atherosclerotic process, leading to symptomatic ischemic heart disease" (StatPearls).

Risk. "Patients with metabolic syndrome are estimated to have a 2-fold increased risk of atherosclerotic cardiovascular diseases and a 5-fold increased risk of diabetes mellitus, as compared to the general population" (StatPearls).

StatPearls: "The diagnosis of metabolic syndrome requires the presence of 3 or more metabolic abnormalities:" "A waist circumference of more than 40 inches in men and 35 inches in women"; "Serum triglycerides level of 150 mg/dL or greater"; "Reduced high-density lipoprotein cholesterol, less than 40 mg/dL in men or less than 50 mg/dL in women"; elevated fasting glucose of 100 mg/dL or greater; "Blood pressure values of systolic 130 mm Hg or higher or diastolic 85 mm Hg or higher."

NHLBI wording. Waist "more than 40 inches for men and 35 inches for women" — "Your provider may use different measurement values for diagnosis, depending on your race and ethnicity." Blood pressure "consistently 130/85 mmHg or higher." HDL "lower than 50 mg/dL for women and lower than 40 mg/dL for men." Triglycerides "consistently more than 150 mg/dL" (StatPearls says 150 or greater). Fasting glucose 100–125 mg/dL is prediabetes; 126 or higher may be diabetes, and "you may have metabolic syndrome if you are taking medicines to treat high blood sugar or diabetes."

StatPearls: "Laparoscopic sleeve gastrectomy, a restrictive weight loss procedure, is the most commonly performed bariatric surgery in the United States"; the Roux-en-Y gastric bypass is second. "The excision of the greater curvature reduces plasma ghrelin levels, a hormone influencing hunger, leading to decreased appetite for most patients." StatPearls (Metabolic Syndrome): "Bariatric surgery is recommended for patients with a BMI ≥40 kg/m2 or those with a BMI ≥35 kg/m2 and other comorbidities."

Early. "Early complications include excessive bleeding, infection, adverse reactions to anesthesia, blood clots, lung or breathing problems, and leaks in the gastrointestinal system." "Bleeding is the most common immediate complication" (StatPearls).

Leak. "Larger leaks can present with more severe symptoms, including marked abdominal pain, tachycardia, fever, leukocytosis, and visible free extravasation of contrast on imaging." "Leaks that present later typically exhibit milder symptoms, such as abdominal pain and tachycardia." "For example, anastomotic leaks or internal hernias can lead to peritonitis, sepsis, and organ failure if not managed quickly and effectively" (StatPearls).

Dumping. "Early dumping syndrome occurs within 30 minutes of eating and is typically caused by rapid gastric emptying, while late dumping syndrome happens 1 to 3 hours after eating, usually due to the release of insulin in response to high sugar levels in the small intestine" (StatPearls, Bariatric Surgery Complications). Late dumping is "characterized by hypoglycemia" (StatPearls, Dumping Syndrome).

Nutrition. "Decreased acid secretion following bariatric surgery predisposes patients to iron-deficiency anemia. Vitamin B1 deficiency after bariatric surgery can present as Wernicke encephalopathy, Korsakoff psychosis, or Beri-Beri." "A deficiency of vitamin B12 can lead to megaloblastic anemia" (StatPearls). "Intrinsic factor, necessary for B12 absorption, is also reduced after RYGB" (StatPearls, Bariatric Malnutrition).