The second-meal phenomenon is associated with enhanced muscle glycogen storage in humans

Clin Sci (Lond). 2009 Jul 2;117(3):119-27. doi: 10.1042/CS20080542.


The rise in blood glucose after lunch is less if breakfast has been eaten. The metabolic basis of this second-meal phenomenon remains uncertain. We hypothesized that storage of ingested glucose as glycogen could be responsible during the post-meal suppression of plasma NEFAs (non-esterified fatty acids; 'free' fatty acids). In the present study we determined the metabolic basis of the second-meal phenomenon. Healthy subjects were studied on two separate days, with breakfast and without breakfast in a random order. We studied metabolic changes after a standardized test lunch labelled with 3 g of 13C-labelled (99%) glucose. Changes in post-prandial muscle glycogen storage were measured using 13C magnetic resonance spectroscopy. The rise in plasma glucose after lunch was significantly less if breakfast had been taken (0.9+/-0.3 compared with 3.2+/-0.3 mmol/l, with and without breakfast respectively; P<0.001), despite comparable insulin responses. Pre-lunch NEFAs were suppressed after breakfast (0.13+/-0.03 compared with 0.51+/-0.04 mmol/l) and levels correlated positively with the maximum glucose rise after lunch (r=0.62, P=0.001). The increase in muscle glycogen signal was greater 5 h after lunch on the breakfast day (103+/-21 compared with 48+/-12 units; P<0.007) and correlated negatively with plasma NEFA concentrations before lunch (r=-0.48, P<0.05). The second-meal effect is associated with priming of muscle glycogen synthesis consequent upon sustained suppression of plasma NEFA concentrations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Glucose / metabolism*
  • Breath Tests
  • Carbon Isotopes / analysis
  • Eating / physiology*
  • Fatty Acids, Nonesterified / metabolism
  • Glucagon / metabolism
  • Glycogen / metabolism*
  • Humans
  • Insulin / metabolism
  • Middle Aged
  • Postprandial Period / physiology
  • Quadriceps Muscle / metabolism*
  • Triglycerides / metabolism


  • Blood Glucose
  • Carbon Isotopes
  • Fatty Acids, Nonesterified
  • Insulin
  • Triglycerides
  • Glycogen
  • Glucagon