Should growth hormone (GH) be administered before workouts or before bed on a fasted stomach?

From the Guidelines

Growth hormone should be administered before bed on a fasted stomach, rather than before workouts, to align with the body's natural circadian rhythm of endogenous GH secretion. This recommendation is based on the study by 1, which suggests that evening injections are preferred to mimic the physiological circadian rhythm of endogenous GH secretion. The study also recommends daily subcutaneous injections, with the injection site changed daily to avoid lipoatrophy.

The timing of GH administration is crucial, and taking it before bed on a fasted stomach allows for optimal absorption and utilization by the body. Food, particularly carbohydrates, can blunt the effectiveness of GH by triggering insulin release, which counteracts some of its metabolic effects. Therefore, it is essential to administer GH when the stomach has been empty for at least 2-3 hours, approximately 30-60 minutes before sleep.

Some key points to consider when administering GH include:

• The bioavailability of GH after subcutaneous injection is approximately 80%, independent of sex 1
• The Tmax of GH is 3–6 hours, and its half-life is 2–3 hours 1
• The typical therapeutic dose ranges from 1-4 IU daily for anti-aging or general health purposes
• Higher doses of 4-8 IU may be prescribed for specific medical conditions
• GH should only be used under medical supervision due to potential side effects, including joint pain, fluid retention, and insulin resistance

Pre-workout administration of GH is generally less effective, as the post-exercise natural GH spike could be disrupted by exogenous administration, potentially interfering with the body's natural hormonal response to exercise. Therefore, administering GH before bed on a fasted stomach is the recommended approach, as it aligns with the body's natural GH secretion pattern and allows for optimal absorption and utilization.

From the Research

Administration Timing of Growth Hormone

The optimal timing for administering growth hormone (GH) in relation to workouts or sleep on a fasted stomach is not directly addressed in the provided studies. However, we can explore the effects of GH administration at different times of the day and its impact on various physiological parameters.

Effects of GH Administration Timing

• A study 2 compared the metabolic effects of GH administered subcutaneously once or twice daily to GH-deficient adults. It found that twice-daily injections were superior in increasing serum IGF-I levels and decreasing IGFBP-1 levels, which tend to amplify the effects of the administered GH.
• Another study 3 investigated the influence of the time of injection on the growth response to GH treatment in short normal children. It concluded that the schedule of injection does not significantly influence the growth response.
• The study 4 on GH response to GHRH before and after meals at different hours of the day in obese patients showed an altered sensitivity of GH secretion to metabolic signals in patients with obesity, with increased GH response after food ingestion at certain times of the day.

Considerations for Administration

• The provided studies do not offer a clear recommendation for the timing of GH administration in relation to workouts or sleep on a fasted stomach.
• However, they suggest that the timing of GH administration can influence its effects on metabolic parameters and growth response, although the optimal timing may depend on individual factors and the specific context of administration.
• It is also important to consider the pulsatile pattern of serum GH and the potential impact of GH administration on the body's natural GH secretion patterns, as discussed in study 5.

GH Administration and Physiological Response

• Study 6 demonstrated that GH treatment can have favorable effects on abdominal/visceral obesity, insulin sensitivity, and lipoprotein metabolism in abdominally obese men.
• The effects of GH administration on physiological parameters can vary depending on the dose, frequency, and timing of administration, as well as individual factors such as age, nutritional status, and metabolic health.