In obese adults without diabetes but with heart disease, weekly injections of semaglutide at 2.4 mg led to a higher rate of patients stopping treatment because of side effects compared to those...
Mechanism
Synthesis from 1 study
This drug makes you eat less, so your body burns fat for energy, which creates harmful waste. But with less food, your body can’t make enough of its natural cleanup tools, so the waste builds up and damages your cells. That’s what makes people feel so sick they stop taking it.
Most probable mechanism
The drug reduces appetite and slows digestion, so the body gets less food and nutrients. To keep running, it starts burning fat for energy, which creates more harmful waste molecules called free radicals. But because there’s not enough food, the body can’t make enough of its natural defenses to clean up those waste molecules. This damages cells, especially in muscles and organs, making people feel sick enough to stop taking the drug.
GLP-1 receptor agonists bind to receptors in the brain and gut, suppressing appetite and delaying gastric emptying
Reduced nutrient intake forces metabolism to rely on fatty acid oxidation to fuel mitochondrial energy production
Increased fatty acid oxidation elevates electron flux through the mitochondrial electron transport chain, raising production of reactive oxygen species
Limited availability of dietary precursors reduces regeneration of NADPH and glutathione, impairing antioxidant defense systems
Oxidative demand exceeds antioxidant capacity, leading to lipid peroxidation and cellular membrane damage
Cellular damage in gastrointestinal, hepatic, and muscular tissues triggers systemic adverse effects such as nausea, fatigue, and muscle weakness
Less supported by current evidence, but not ruled out
The drug causes people to eat less, which signals the body to slow down muscle building and speed up muscle breakdown. This leads to loss of muscle, which can cause weakness and fatigue, making people stop taking the drug.
GLP-1 receptor agonists reduce nutrient and amino acid intake
Low nutrient levels activate AMPK, an energy-sensing enzyme that inhibits mTOR, a key regulator of protein synthesis
Inhibited mTOR reduces ribosomal activity and muscle protein synthesis
Net loss of skeletal muscle mass occurs due to ongoing proteolysis without adequate replacement
Muscle weakness and fatigue contribute to treatment-limiting adverse events
The drug slows digestion and reduces food intake, which makes it harder for the body to absorb essential vitamins and minerals like iron, magnesium, and selenium. Without these, key enzymes that produce energy and fight damage don’t work well, leading to tiredness, organ stress, and side effects that cause people to quit the drug.
GLP-1 receptor agonists delay gastric emptying and alter bile acid dynamics
Reduced bile acid activity impairs absorption of fat-soluble micronutrients including selenium, magnesium, and iron
Micronutrient insufficiency reduces catalytic efficiency of mitochondrial enzymes and antioxidant proteins like SOD and GPX4
Impaired enzyme function reduces ATP production and antioxidant defense, increasing cellular stress
Systemic metabolic inefficiency and oxidative stress manifest as fatigue, gastrointestinal distress, and other adverse events
Evidence from Studies
Supporting (1)
Community contributions welcome
Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes.
Contradicting (0)
Community contributions welcome
Gold Standard Evidence Needed
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