The new drugs are the first to manipulate the hormonal regulatory systems governing energy balance. The drugs simulate the action of our native GLP-1 but with longer-lasting effects, amplifying the fullness signal inside the body. People who struggle to feel sated suddenly don’t, effectively giving “someone the ‘will power’ of those lucky enough to have won the genetic lottery,” said Dr. Brierley.
Many people who have taken the medicines for obesity described to me how their experience of hunger had fundamentally changed. Patricia McEwan, who has injected Ozempic for nine months, said she planned to stay on the drug for life because it “shut off the intrusive constant thoughts about food” that had consumed too much of her mental space since childhood. Before Ozempic, Ms. McEwan thought her overeating was driven by her emotions and lack of will power. After Ozempic, she understood that how she responded to food was the product of her physiology.
There are open questions about how GLP-1-based drugs will work long term in individual patients, and what impact, if any, they’ll have on the surging global obesity rate. The data we have suggests people’s weight loss can plateau after a while, side effects are common, as is weight regain when patients go off the medicines.
There have been many reports about insurance hurdles or supply shortages that interrupt or block people’s access to obesity drugs in the United States, and it’s unclear how low-income people will get access to them. Meanwhile, the energy balance model of appetite regulation is being complicated by evidence that we have other kinds of nutrient appetites — for protein, for example — and there’s very little understanding of how the medicines will affect these.
At the very least, though, the way the drugs work can teach us that people who are larger did not necessarily choose to be, just as people who are smaller did not — and are not morally superior. This “isn’t a free pass, either to individuals who do have the capacity to choose better, nor does it take the heat off of food industries,” said a University of Sydney nutritional biologist, Stephen Simpson, but it’s “evidence that obesity isn’t a personal lifestyle choice.”
Learning about this science helped me see my own weight changes in a new light. When I became pregnant with my second child, I very quickly developed a voracious appetite. I felt a pain from hunger I’d never experienced, would obsess about my next snack or meal in ways I don’t usually, and ate quantities I would have found unimaginable (even unbearable) a few weeks prior. I also gained weight rapidly.
Suddenly in my second trimester, the increased appetite, and the weight gain, eased. But the preoccupation with food I’d just experienced recalled my earlier years, when I struggled with obesity. Now, I could see the changes were not the result of a sudden shortage in will power. My brain was telling my body to get more energy to support the growing fetus.