The Study
Substrate Metabolism and Insulin Sensitivity During Fasting in Obese Human Subjects: Impact of GH Blockade
This study is like a carefully controlled experiment where 9 men were studied under three different conditions in random order. Because the conditions were randomly assigned, we can say the GH blocker actually caused some of the changes seen, not just that they happened together. However, with only 9 people, we can't be super confident these results would happen in all obese people - it's like tasting one spoonful of soup and deciding you know how the whole pot tastes.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Researchers gave obese men a drug (pegvisomant) to block growth hormone while they fasted for 3 days. They compared this to normal fasting and a regular fed state. The drug helped their bodies respond better to insulin and produce less glucose.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 573 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes - this is significant for humans.
- 2The study shows that GH contributes to insulin resistance during fasting in obese people, and blocking GH almost completely reverses this effect.
- 3GH levels rose during fasting.
- 4Blocking GH reduced insulin resistance by 99% (P<0.01).
- 5Endogenous glucose production dropped significantly (P=0.003).
- 6Lipid intermediates were more suppressed during insulin clamp.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The Journal of Clinical Endocrinology & Metabolism
Year
2017
Authors
M. H. Pedersen, M. Svart, J. Lebeck, M. Bidlingmaier, H. Stødkilde-Jørgensen, S. Pedersen, N. Møller, N. Jessen, J. Jørgensen
Related Content
Claims (10)
When no food is consumed during fasting, insulin levels drop, leading to the breakdown of fat stores and increased burning of fat in the liver.
In obese men, not eating for 72 hours raises growth hormone levels and lowers IGF-I levels; when growth hormone signaling is blocked with pegvisomant, IGF-I levels drop further, confirming that pegvisomant blocks growth hormone activity in this group.
In obese men, a 72-hour fast causes insulin resistance by increasing the liver's production of glucose, and blocking the hormone growth hormone with pegvisomant reduces this insulin resistance by lowering liver glucose output by about 30%, showing that growth hormone is necessary for this effect.
In obese men who fast for three days, blocking the hormone growth hormone with a drug called pegvisomant allows insulin to reduce fat breakdown more effectively, leading to lower levels of free fatty acids and ketones than fasting alone.
In obese men, going without food for 72 hours raises glycerol levels and lowers cortisol and glucagon levels when growth hormone is blocked, showing that growth hormone influences the body's hormonal response to extended fasting.
When men with obesity fast for 3 days while also blocking growth hormone, their bodies become better at using insulin again.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.