You're combining two separate ideas: natural GH release and injected GH. High glucose/insulin can suppress your body's natural GH release, which is where the advice to take GH on an empty stomach and avoid carbs comes from. However, once you inject GH, insulin won't negate that GH. So I wouldn't stress too much about whether eating carbs shortly before a bedtime GH shot is a waste. I'd approach it more from a glucose management perspective. GH can temporarily decrease insulin sensitivity and glucose uptake, and having higher GH levels over time can worsen glucose tolerance. So consuming a large carb meal right around the GH injection might not be the best for your metabolism, even if it doesn't really diminish the GH's effectiveness. The retatrutide adds complexity to the timing as well. It can delay gastric emptying, so saying “I had carbs two hours before GH” doesn’t guarantee those nutrients are fully absorbed by the time you inject. The extent of gastric-emptying delay can also vary over time. Regarding metformin: I haven't found any solid evidence that taking metformin with GH significantly reduces the effects of injected GH. There are studies where GH and metformin were given together, and IGF-1 still increased a lot. In randomized trials, metformin hasn't shown a consistent significant decrease in IGF-1 in adults either. So I wouldn't change my entire eating routine just to create a longer “fasted GH window.” If you need to eat closer to bedtime to get your calories and macros in, I'd…
