Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by insulin resistance, hyperandrogenism, and reproductive dysfunction. Dietary strategies that improve postprandial insulin and glucose responses are central to managing metabolic symptoms in PCOS.
Meals higher in protein can attenuate postprandial glycemia and enhance satiety, but the effects may vary by protein source. Animal sources of protein typically have higher essential amino acid content and insulinogenic potential, whereas plant proteins offer fiber and phytochemicals that may influence glycemic dynamics differently. Few studies have directly compared the acute metabolic effects of plant versus animal protein in women with PCOS. Given the distinct pathophysiology of PCOS, extrapolating findings from healthy populations may be misleading.
Understanding protein-specific effects on postprandial insulin, glucose, and appetite-regulating hormones in this group is essential for targeted nutrition guidance. Additionally, plant-based diets are increasingly promoted for cardiometabolic health, but their acute effects in insulin-resistant women remain underexplored. This study will assess whether plant and animal protein meals elicit differential postprandial responses in women with PCOS. Findings may inform dietary recommendations aimed at improving metabolic outcomes in this high-risk population.
Females ages 18-50 years
Confirmed diagnosis of PCOS
Body mass index (BMI) between 18.5 and 35 kg/m2
Stable body weight for at least 3 months (+ 5 pounds)
Smoking or use of nicotine products
Smoking or use of marijuana products
Food allergies or dietary restrictions incompatible with test meals
Diagnosed diabetes (type 1 or 2)
Crossover
Metabolic response to protein source
Other interventionParticipants will be given a 350-400 kcal meal challenge containing 30% energy from animal protein. They will be given 10 minutes to consume the meal and meal response will be measured 240 minutes following the meal.
Energy expenditure
Energy expenditure will be measured using indirect calorimetry.
Appetite
Participants will be asked to rate their perceived hunger, fullness, and desire to eat with the use of a traditional 100 mm visual analog scales (VAS) with opposing anchors (e.g., "extremely hungry" or "not hungry at all"). The questions include "how hungry do you feel at this moment," "how full do you feel at this moment," "how strong is your desire to eat at this moment," and "how much food do you think you could eat at this moment." Participants will also be asked to evaluate the appearance ("how much do you like or dislike the appearance of the breakfast foods") and palatability ("how much do you like or dislike the smell and taste of the breakfast foods") of the breakfast with the use of a traditional 100 mm visual analog scale with opposing anchors "dislike extremely" or "like extremely." Appetite assessments were measured at 0, 15, 30, 60, 120, and 240 min after the meal.
Plasma amino acid response
Plasma amino acids will be measured using UPLC
Plasma biomarkers related to appetite
Appetite biomarkers including PYY (Peptide YY), CCK (cholecystokinin), BDNF (brain-derived neurotrophic factor), GLP-1 (glucagon-like petide-1), and ghrelin will be measured using commercially available kits. This measurements will be interpreted together to make a conclusion about a appetite regulation in response to protein source.
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