Western diets rich in animal protein and poor in fruit and vegetables increase the body acid load, a predictor of type 2 diabetes risk. The relationships between dietary acid load, mild metabolic acidosis and insulin resistance remain unclear.

The objective of this study was to assess the association between dietary acid load, body acid/base markers and peripheral insulin resistance at baseline and following a short-term overfeeding intervention in healthy individuals. In a cross-sectional study of 104 men and women, insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp. Plasma lactate, a marker of metabolic acidosis, was assessed and acid load scores (potential renal acid load, PRAL and net endogenous acid production, NEAP) derived from diet diaries.

The cohort was grouped into lean and overweight/obese and the latter further classified as insulin-sensitive (Obsen) and insulin-resistant (Obres) based on hyperinsulinemic-euglycemic clamp glucose infusion rate (GIR, top tertile vs. bottom 2 tertiles).