What does Mounjaro specifically target in the body?

Mounjaro targets two key hormone receptors in the body — GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). These hormones help regulate blood sugar, appetite, and energy use. By acting on both, Mounjaro improves how your body handles glucose while also curbing hunger, helping support steady, sustainable weight loss.

How the GIP and GLP-1 hormones work

Both GIP and GLP-1 are naturally released from the gut after eating. They signal the pancreas to release insulin and tell the liver to reduce glucose production. GLP-1 also slows gastric emptying, which contributes to feeling full after meals. NICE (TA1026, 2025) explains that tirzepatide, the active ingredient in Mounjaro, mimics these natural hormones to enhance the body’s own blood-sugar control mechanisms. This dual-receptor action is what sets it apart from medicines that act only on GLP-1. NHS clinicians describe the combination as a “complementary effect” that helps smooth insulin release and appetite signals.

Why dual-receptor activation matters

The GIP receptor sits mainly in the pancreas and fat tissue, while GLP-1 receptors are spread across the pancreas, stomach, and brain. By stimulating both, Mounjaro influences not only insulin production but also how energy is stored and used. NICE evidence shows this combination produces greater average weight reduction than single-pathway drugs. In The Lancet Diabetes & Endocrinology pooled analyses, participants using tirzepatide lost up to 22.5 % of body weight over longer trials—significantly more than with earlier GLP-1 analogues. Researchers think GIP signalling helps fine-tune energy metabolism and may lessen some gastrointestinal side effects. A few people have shared that they feel steadier when they introduce gentle physical activity as their metabolism changes. NHS weight-management programmes often reinforce that combining medicine with daily movement helps stabilise blood-sugar swings and preserve lean muscle mass.

Effects on appetite, digestion, and energy balance

Mounjaro’s action in the gut–brain axis helps explain its effects on hunger and satiety. GLP-1 receptor stimulation sends signals to appetite-control centres in the brainstem and hypothalamus, while GIP input may reinforce that signal. Together they reduce cravings and slow the rate of food absorption. Some people have found it helpful to eat smaller portions and focus on protein-rich foods, which can make meals more satisfying without overeating. NHS weight-management services often suggest practical meal-timing strategies to align with Mounjaro’s slower digestion pattern. Several users have said they feel more confident after they learn that the “fuller for longer” sensation is an intended effect, not a side effect. Recognising that this response means the receptors are working often reassures people during the first few weeks of therapy.

How this supports glucose control

For people living with type 2 diabetes, tirzepatide’s dual action improves both fasting and post-meal glucose readings. By enhancing insulin sensitivity and moderating glucagon release, it helps keep blood-sugar levels within a healthier range throughout the day. NICE data show that many users achieved average HbA1c reductions of around 2 percentage points in clinical studies—larger than with most single-hormone GLP-1 agents. In real-world use, many have discovered that steady meal routines and regular physical activity further strengthen this effect. People frequently tell clinicians that it helps to pair injections with consistent eating schedules to avoid low-energy dips. A practical tip many people use is to inject on the same day each week after breakfast, which can make it easier to remember and keeps glucose patterns predictable. NHS educators note that this regular rhythm also supports long-term adherence.

Broader effects on metabolic health

The influence of GIP and GLP-1 pathways reaches beyond weight and glucose. Studies referenced by NICE and the MHRA suggest tirzepatide can reduce liver fat and improve certain markers linked to heart health, such as blood pressure and cholesterol levels. These effects likely come from improved insulin action and lower inflammation in fat tissue. In Nature Medicine (2025), investigators reported that participants receiving tirzepatide showed favourable shifts in energy expenditure—essentially how efficiently the body uses stored fuel. Those using Mounjaro often find it useful to see these improvements as part of a wider wellbeing journey rather than focusing solely on the number on the scales. Over time, better metabolic balance may also lessen risks associated with type 2 diabetes and cardiovascular disease.

Research on future potential

International research continues to map where else these receptors may play a role. Trials in JAMA Network Open and New England Journal of Medicine are exploring whether tirzepatide’s activity might benefit conditions such as obstructive sleep apnoea and fatty-liver disease. Early findings show promising improvements in both breathing quality during sleep and liver-enzyme profiles. It’s generally easier to stay consistent when you keep appointments for follow-up reviews. NHS specialists use these sessions to check progress, adjust doses, and discuss lab results, ensuring that benefits extend safely over the long term.

What the evidence shows overall

Mounjaro’s design—targeting both GIP and GLP-1 receptors—marks a major evolution in weight-management and diabetes care. Each hormone contributes distinct but complementary effects, and together they create a coordinated system that regulates appetite, digestion, and glucose metabolism.

 By understanding these targets, users and clinicians can set more realistic expectations and plan treatment confidently. Evidence from NICE, NHS, and major journals shows that this dual-pathway approach represents one of the clearest scientific advances in how medicines support long-term metabolic health. The broader research picture continues to confirm that addressing multiple hormonal routes can help people not only lose weight but sustain healthier metabolism over time.