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Human growth hormone (hGH) plays a crucial role in how the human body grows and maintains its metabolism. It has been observed to influence various metabolic processes within the body, but does hGH make you hungry?
This is a complex question that may not have a clear-cut answer based on the available scientific data. That is because hGH regulates metabolism and hormonal balance on many different levels.
In this article, we will explore the intricate relationship between growth hormone (hGH) and appetite, examining the mechanisms by which human growth hormone may influence hunger and metabolic processes. We will also review the current scientific research to provide insights into how hGH injections might affect hunger levels and overall body weight.
Does Growth Hormone Increase Your Appetite?
The natural production of human growth hormone and other hormones directly stimulated by it, such as its main anabolic mediator called insulin-like growth factor-1 (IGF-1), appear to affect appetite and hunger via three main mechanisms, including:
- influencing brain regions related to hunger
- interactions with blood sugar and insulin levels
- modulating appetite hormones (GLP-1 and ghrelin)
For instance, hGH and IGF-1 may directly interact with different neurons in a part of the brain called the hypothalamus, which is known to regulate appetite. However, the available scientific information so far suggests that these interactions remain largely unknown and more research is needed.
Moreover, hGH and IGF-1 may reduce both GLP-1 (appetite suppressant) and ghrelin levels (a hunger hormone), leaving the overall effect neutral.
Furthermore, hGH and IGF-1 interact with blood sugar and insulin levels and can influence appetite. During the natural peaks in human growth hormone production, it counteracts insulin, preventing blood sugar drops and potentially reducing hunger.
However, over time, higher hGH levels may also elevate IGF-1 levels, which mimic insulin and may decrease blood sugar levels. Very high human growth hormone therapy is also linked to insulin resistance, leading to unstable blood sugar and sudden hunger changes.
Therefore, the effect of hGH on appetite may depend on its levels, with higher human growth hormone doses potentially increasing appetite in the long term.
Further research suggests that poor appetite is a common symptom in children with decreased natural growth hormone synthesis, aka human growth hormone deficiency (GHD). According to the data, it may affect as much as a third of the children, based on the reports of their parents.
Thus, having normal human growth hormone levels may have a neutral effect on hunger, while GHD may result in reduced appetite and energy levels.
In contrast, having very high hGH may increase hunger due to its actions on tissue growth and proliferation, and also lead to metabolic problems associated with appetite changes.
Do hGH Injections Make You Hungry?
Properly dosed growth hormone replacement therapy (hGH therapy) may help normalize hunger levels according to the organism’s physiological state.
In other words, injections of growth hormone can stimulate hunger to a degree, which is important for normal growth in children and muscle mass restoration in adults with decreased natural growth hormone synthesis due to GHD.
Studies in children with GHD consistently show that hGH treatment increases appetite and food intake, but only to align it with their increased growth, body weight, and energy requirements:
- A short trial with 46 children with health conditions related to low GH such as Turner syndrome (TS) or Silver Russell syndrome (SRS) found that, over 3 days, the hGH group consumed about 1308 more kcal, 52g more protein, 61.5g more fat, and 145g more carbs compared to placebo. The GH therapy increased basal metabolic rate, fat-free mass, and reduced body fat, likely contributing to higher food intake.
- A small 12-month trial with 9 children with idiopathic short stature (ISS) reported significant increases in height, weight, and BMI, along with a higher metabolic rate. Appetite, total energy (+321 kcal), and protein (+13.9g) consumption increased, along with more snacks per day. Postprandial and fasting ghrelin levels decreased, fasting GLP-1 levels decreased, and fasting insulin levels increased, with no change in leptin levels.
In adults, GHD may lead to reduced appetite, which hGH injections can normalize. However, research shows no significant increase in food consumption following therapy:
- A 6-month trial in 25 individuals with adult growth hormone deficiency taking hGH therapy reported increases in lean body mass and thyroid hormones, with only a trend toward higher energy intake. Fat decreased, leading to stable body weight.
- Another 6-month trial in 19 adults with growth hormone deficiency taking 0.3mg/daily of hGH reported increased hunger levels before meals compared to placebo, but overall food intake did not change. Interestingly, the hGH group had better control over dietary choices and food intake. Body weight remained stable, voluntary physical activity doubled, and quality of life improved in the hGH group.
Can hGH Cause Weight Gain?
Recombinant hGH therapy typically reduces adiposity, helping to reverse the increase in body fat storage typically seen in individuals with GHD. However, some patients may experience less weight loss than anticipated.
This is because human growth hormone therapy increases lean body mass, which can offset the reduction in fat mass, resulting in no net change in body weight.
In fact, studies suggest that the increase in lean mass can sometimes exceed the reduction in body fat, leading to a net weight gain.
Therefore, changes in body weight may not accurately reflect the reduction in body fat percentage. Despite the minimal net change in body weight, patients can still lose several inches from their waist and appear leaner.
Body weight increases during human growth hormone therapy can also be attributed to the retention of body fluids, which is temporary. However, if calorie intake consistently exceeds caloric expenditure, weight gain will occur regardless of any medication or therapy.
Therefore, it is advisable to combine hGH treatment with increased physical activity and reduced energy intake. The key to sustainability is choosing an enjoyable activity that boosts energy expenditure.
Additionally, a balanced diet, primarily consisting of whole, unprocessed foods and enough lean proteins, is crucial. These foods are generally lower in calories and more satiating than highly processed alternatives, making it much easier to stick to a low-energy healthy diet.