Impact of Asprosin and Neuregulin 4 on Metabolic Parameters, Anthropometric Indices and Body Composition After Laparoscopic Sleeve Gastrectomy

within-participant change from baseline in log-transformed fasting serum asprosin and NRG4.

Weight is measured to 0.1 kg on a calibrated platform scale in the morning after the fasting draw. Waist and hip circumferences are the mean of three readings, with a fourth taken if the range exceeds 1 cm. Two trained observers perform all anthropometry; inter-observer reliability is established before enrolment and an intraclass correlation below 0.95 for any circumference requires retraining.

Body composition is measured on a single InBody 120 segmental analyser (InBody Co. Ltd., Seoul, South Korea) for the entire study, the platform used in this group's published body-composition work, which preserves comparability with that cohort. Measurement is standardised to the morning, fasting, post-void state with no exercise for 12 hours, no alcohol for 24 hours, light clothing, bare feet, and the same room and device at every visit. Recorded variables are body fat mass and percentage, body muscle mass and percentage, fat-free mass, skeletal muscle mass, visceral fat, total, intracellular and extracellular water, and the derived fat mass index, fat-free mass index, skeletal muscle mass index and the proportion of weight lost as fat-free mass.

The Triglyceride-Glucose (TyG) index is a simple, reliable blood marker used to measure insulin resistance and cardiometabolic risk.

Normal and High-Risk Ranges:

Optimal: A TyG index under 4.49 (using specific standard scales) or lower values generally point to healthy metabolic function.

Insulin Resistance: Values above standard cutoffs (often varying by population, with high risk frequently cited at ≥ 8.77 or ≥ 9.04 depending on the specific diagnostic calibration) suggest the body is struggling to process insulin properly.

A lipid profile is a blood test that measures the amount of cholesterol and fats in your blood to check your risk for heart disease.

Total Cholesterol: The overall amount of cholesterol in your blood. A normal level is below 200 mg/dL.LDL (Low-Density Lipoprotein): The "bad" cholesterol that can block your blood vessels. A normal level is below 100 mg/dL.HDL (High-Density Lipoprotein): The "good" cholesterol that helps clear bad cholesterol away. A higher level (above 60 mg/dL) protects your heart.Triglycerides: A type of fat stored for energy. A normal level is below 150 mg/dL.VLDL (Very Low-Density Lipoprotein): A type of bad fat that carries triglycerides. A normal level is below 30 mg/dL.

The AST/ALT ratio (also called the De Ritis ratio) compares two liver enzymes in your blood to help doctors find the cause of liver or muscle damage.

Less than 1.0: ALT is higher than AST. This is common in metabolic fatty liver stress or viral hepatitis.

Around 1.0 to 1.2: AST and ALT are balanced or slightly raised together, which can happen with early liver stress or viral infections.

1.2 to 2.0: AST is higher than ALT. This can point to advanced liver scarring (fibrosis), cirrhosis, or recent intense exercise.

Greater than 2.0: AST is more than double ALT. This strongly suggests alcohol-related liver injury or alcoholic hepatitis.

Non-liver causes: Because AST is also found in heart and skeletal muscles, high AST (and a high ratio) can happen after severe muscle damage or a heart event.

hs-CRP (high-sensitivity C-reactive protein) is a blood test that measures low levels of inflammation in the body to help assess your risk of heart disease.

Results are measured in milligrams per liter (mg/L):

Low risk: Less than 1.0 mg/L Average or moderate risk: 1.0 to 3.0 mg/L High risk: Above 3.0 mg/L Very high (above 10 mg/L): Usually points to a current infection or acute injury rather than long-term heart risk.

Leptin is a hormone made mostly by fat cells that helps your body manage energy balance and long-term appetite.

Males (Normal BMI): [0.5 to 12.5 nanograms per milliliter (ng/mL)](0.6.1, 0.6.2) Females (Normal BMI): [0.5 to 15.2 ng/mL](0.6.1, 0.6.2) (women often show higher levels than men at comparable body fat due to estrogen effects).

Obese Individuals (Any Sex): Typically range from 20 to 100+ ng/mL, which often reflects a leptin resistance pattern rather than simple excess.

Deficient Levels: Below 0.5 ng/mL can indicate true deficiency or severe malnutrition/over-dieting

Adiponectin is a protective protein hormone secreted by fat tissue that helps regulate glucose levels, break down fatty acids, and lower systemic inflammation.

Normal Range: Typically ranges from 5 to 37 µg/mL depending on your body mass index (BMI) and sex.

Low Levels: Connected to obesity, type 2 diabetes, metabolic syndrome, and heart disease.

Ghrelin is a peptide hormone produced mainly by the stomach that signals your brain to stimulate appetite and increase food intake.

The normal reference range for total ghrelin in plasma typically spans from 100 to 1,200 pg/mL in healthy adults, though specific values change based on whether you are fasting or have recently eaten:

Fasting state: Levels rise to stimulate hunger, often ranging between 500 and 2,500 pg/mL.

Postprandial state (after eating): Levels drop significantly, usually falling between 100 and 900 pg/mL.

Normal-weight controls: Specific reference panels often cite a baseline fasting range of 520 to 700 pg/mL.