By Dr. Asnat Raziel, bariatric surgeon specializing in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal, Tel Aviv
What are the types of obesity, and why do they matter?
The types of obesity offer a new way to understand why people gain weight. They also help explain why the same treatment works brilliantly for one person and fails for another. After all, obesity is not a single, uniform disease. It arises from a mix of biology, behavior and environment, so once we identify the main mechanism driving it, we can tailor treatment with real precision.
Researchers at Mayo Clinic, led by Dr. Andres Acosta, identified four types of obesity, or phenotypes. A phenotype is a pattern of measurable traits in the body and in behavior. This approach is part of precision medicine, which chooses treatment according to the underlying mechanism rather than weight alone.
Four types of obesity: what Mayo Clinic found
In a study published in 2021 in the journal Obesity, researchers evaluated 450 people with obesity. They measured fullness during a meal, how quickly the stomach empties, emotional eating and resting energy expenditure. In 383 of them (85%), they identified at least one phenotype. In the remaining 15%, no clear phenotype emerged, and 27% of participants had two or more.
Hungry brain: fullness arrives too late
In this type, fullness during a meal arrives late. The gut-brain axis fails to deliver satiety signals on time, so the person needs a large amount of food before feeling full. To measure it, the Mayo team uses an all-you-can-eat buffet meal and counts how many calories the person eats before feeling full.
For instance, picture someone who finishes a big plate of pasta and still feels they could keep going. In the study, these patients received phentermine-topiramate. Today we also use GLP-1 medications such as Wegovy and Mounjaro, which strengthen satiety signals in the brain. Razin (phentermine) can also help reduce appetite.
Hungry gut: hunger comes back quickly
Here the problem lies in the fullness that should follow a meal. The stomach empties faster than normal, and the feeling of fullness fades soon after eating. To assess it, Mayo clinicians use a gastric emptying scan. For example, someone eats a full breakfast of eggs and vegetables and is already looking for a snack an hour later.
In the study, these patients received liraglutide, an older GLP-1 medication. Today, Wegovy and Mounjaro slow gastric emptying and prolong fullness. In severe obesity, sleeve gastrectomy or gastric bypass surgery also raises satiety hormones.
Emotional hunger: food as comfort
This is a behavioral type. Stress, sadness, boredom or anxiety, rather than physical hunger, drive the eating. The brain’s reward system, which works through dopamine, plays a central role. For example, someone has eaten a large meal, yet after a stressful day reaches for chocolate anyway. To identify it, Mayo clinicians use a validated anxiety questionnaire.
In the study, these patients received naltrexone-bupropion, marketed in Israel as Mysimba. Alongside the medication, we also recommend cognitive behavioral therapy (CBT); it teaches people to recognize patterns and change them. When binge eating is present, it is worth knowing that the FDA approved Vyvanse in 2015 for moderate to severe binge eating disorder. It is not, however, intended for weight loss.
Slow burn: a metabolism in low gear
In this type, the body burns less energy at rest than would be expected for its size. These are people who watch what they eat and exercise, yet the scale barely moves. To measure resting metabolic rate (RMR), clinicians use indirect calorimetry. The test measures oxygen consumption and carbon dioxide output through a mask and takes about half an hour.
In the study, these patients received phentermine. Strength training and protein at every meal also help preserve muscle mass. It is worth checking the thyroid as well, to rule out an underactive gland.
Treatment by type of obesity: what the studies showed
In the same study, the researchers divided 312 patients into two groups. One group received medication matched to their phenotype; the other received medication without matching. After one year, the matched group had lost 15.9% of their body weight, compared with 9.0% in the other group, a weight loss 1.75 times greater. What’s more, 79% of the matched patients lost more than 10% of their weight, compared with only 34% in the standard group.
That said, it is important to be precise. This was a pragmatic study at a single clinic, using older medications. It also did not include semaglutide or tirzepatide. In the STEP 1 trial, Wegovy led to an average weight loss of 14.9% after 68 weeks. In the SURMOUNT-1 trial, Mounjaro at 15 mg led to a 20.9% loss after 72 weeks.
Lifestyle programs benefit from tailoring too. The PHENO-Diet trial enrolled 165 adults for 12 weeks. The tailored-program group lost 7.4 kg, compared with 4.3 kg on the standard program. People with a hungry brain received a high-volume meal plan with a restricted eating window. Those with a hungry gut received protein before meals. Those with emotional hunger received intensive behavioral therapy. Finally, those with a slow burn received HIIT (high-intensity interval training) and protein after exercise. However, the trial was not randomized, which is why the researchers are calling for a controlled trial.
What’s new in the research
In 2026, the Mayo group published a hungry-gut subtype in the journal Gastroenterology. Among the 483 participants, 26.9% had rapid gastric emptying and low GLP-1 levels after meals. In a retrospective analysis of 61 patients, this subtype lost 21.5% of body weight after six months on tirzepatide, compared with 11.7% for the other patients.
Meanwhile, an American company has developed a genetic test to identify the hungry gut. At the DDW 2024 conference, researchers presented data on 84 patients taking semaglutide. Those the test identified as having a hungry gut lost 19.5% of their weight over a year, compared with 10% for the rest. These are conference data, presented in collaboration with the developing company, and they have not yet been fully published in a journal.
A 2025 review concluded that the approach is promising but that large randomized trials are still lacking. For now, phenotypes are a helpful aid to clinical thinking, not a substitute for medical judgment. They fit well within the European framework for personalized obesity care.
Self-check questionnaire: which type of hunger stands out for you?
The following questionnaire is based on the features described in the studies. It is not the Mayo test and it is not a validated tool. Instead, think of it as a starting point for a conversation with your doctor. Rate each statement from 1 (not true for me at all) to 5 (very true for me), and add up each group separately.
Hungry brain:
- I need a large meal to feel full.
- During a meal, my brain doesn’t signal me to stop.
- My meals are bigger than those of the people around me.
- The feeling of fullness comes late for me.
- Even after a large portion, I’m still hungry.
Hungry gut:
- Less than two hours after a full meal, I’m hungry again.
- My feeling of fullness disappears quickly.
- I need small, frequent meals to keep going.
- After eating, I get an energy slump and my hunger returns.
- My stomach feels empty soon after a meal.
Emotional hunger:
- Stress, sadness or boredom make me eat.
- Even without physical hunger, I get an urge for comfort food.
- When I’m in a bad mood, I choose less healthy food.
- At celebrations and parties, I eat regardless of hunger.
- Anxiety leads me to eat at night or between meals.
Slow burn:
- Despite a balanced diet and exercise, I find it hard to lose weight.
- It seems to me that my body burns calories slowly.
- Chronic fatigue is with me most of the time.
- I often feel cold when others are comfortable.
- Compared with others, my weight loss is very slow.
A score of 16 or more in a group suggests that this type is prominent for you. A score of 11 to 15 indicates partial features. Only a medical assessment, however, can give you the full picture.
Overlap between types of obesity
About a quarter of patients show two or more phenotypes, for example a hungry brain together with emotional hunger. In such cases, a multidisciplinary approach that addresses all the mechanisms at once works best. Sometimes the doctor combines a GLP-1 medication with Razin, as a medical decision and under close follow-up.
There is also a phenomenon that appears across all four types and is worth knowing about: a constant preoccupation with food, often called “food noise.” I have written about the chemistry that drives hunger and how it connects to these types. The season matters too, as I explained in an article about winter hunger.
A lifestyle that suits every type
For all types of obesity, I recommend a protein-rich diet, with about 25 to 30 grams of protein at each meal. In addition, plenty of vegetables provide fiber and prolong fullness. Strength training, adequate hydration and 7 to 9 hours of sleep a night are important as well.
The mind needs a place in the plan, too. For example, yoga, tai chi or meditation reduce stress. Vacations, time in nature and get-togethers with friends prevent burnout. And personal goals and hobbies strengthen motivation over the long term.
The bottom line on types of obesity
Understanding that there are different types of obesity shifts the question from “how much should I eat?” to “why do I eat?” Early data show that matching treatment to the mechanism increases weight loss. Still, the research is evolving, and the full tests are not available everywhere. That’s why it is wise to build your plan with a team that includes a doctor, a dietitian and a mental health professional. Ultimately, the goal is not just to shed kilograms, but to build a strong body and a balanced mind.
The information in this article is general and does not replace personal medical advice.
References
Precision Prevention, Diagnostics, and Treatment of Obesity: Pipedream or Reality?
Once-Weekly Semaglutide in Adults with Overweight or Obesity
Tirzepatide Once Weekly for the Treatment of Obesity
Study Demonstrates MyPhenome Hungry Gut Test Identifies Responders to Semaglutide
Mayo Clinic and the NIH funded the PHENO-Diet trial. Novo Nordisk funded the STEP 1 trial, and Eli Lilly funded SURMOUNT-1. The genetic test data were presented in collaboration with the developing company.
