The most influential drugs recently released are categorized as GLP-1 agonists. This means the drugs work similarly to GLP-1. GLP-1 stands for Glucagon-like Peptide-1, and how GLP-1 works in the body explains why drugs that mimic its activity in the body, called GLP-1 agonists, appear to be effective at promoting weight loss, and they do it quickly. Among the functions of GLP-1 is regulating hunger, and the drugs that mimic its action can significantly reduce the desire to eat. That leads to less total calorie intake, translating into significant weight loss. However, one thing overlooked about these GLP-1 agonist drugs is that up to 40% of the weight lost when using the drugs consists of lean mass or muscle. Whenever a calorie-restricted diet is used, some muscle is lost. Under the best circumstances, the extent of muscle loss with diets is only 5 to 10% of total weight loss, with the rest being body fat. However, without the accompaniment of resistance training, any caloric deficit, including that which results from using GLP-1 agonist drugs, will induce significant loss of muscle mass. Along with that loss of muscle, the resting metabolic rate declines. That means you would need to eat significantly less food or calories to maintain the lost weight, which most people cannot do for an extended time. For that reason, 95% of people who lose weight on a diet gain it back within a year. The same is true for the GLP-1 agonist drugs. When most people get off the drugs, their appetite returns to normal, and so does their lost body fat.
The original goal of GLP-1 agonist drugs was to treat diabetes. That is because GLP-1 acts as an "incretin," which promotes insulin release from the pancreas. However, it soon became evident that diabetic patients who were prescribed the drugs showed significantly reduced appetites along with significant weight loss. Drug companies noted that and repackaged some of the GLP-1 agonist drugs as weight-loss drugs. Two of them, with the trade names Wegovy and Saxenda, are prescribed for weight control. These drugs reduce appetite because they delay stomach emptying after a meal, making a person feel full for a longer time with less desire to eat more food. The drugs are called GLP-1 agonists because they bind to the same receptors in the gastrointestinal tract that natural GLP-1 does. However, natural GLP-1 has a short-lived effect because it's degraded in only 1 to 2 minutes by an enzyme called dipeptidyl peptidase-4 or DPP-4. Other drugs and the GLP-1 agonist drugs work to blunt the actions of DPP-4, thus extending the activity of the drugs.
The popular GLP-1 agonist drug is semaglutide, sold under the trade name, Wegovy. As noted, this GLP-1 agonist . . .
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