Have you ever sat with a friend during a mid-afternoon break and watched her eat just one cookie, while you’re trying to stop yourself from devouring the bagful? Or been at a buffet with someone who has only one serving of her main course and doesn’t go back for more? Maybe you know someone who never gains weight, even though she eats as much as you (so unfair!). Or you have that friend who loses weight when she’s upset, because she ‘stress starves’ rather than stress eats. It turns out the reason these people have different eating behaviors to you is because they demonstrate different types of hunger and/or metabolism from yours.
Obesity Phenotypes
Dr Andres Acosta, MD, PhD, is the director of the Precision Medicine for Obesity Laboratory at the Mayo Clinic in Rochester, MN. He and his team have identified various observable characteristics (i.e., phenotypes) that contribute to the way people feel hungry (take in calories) or use energy (burn off calories).1 Using a combination of eating studies, imaging and various questionnaires in a group of 450 people with a BMI >30 kg/m2, they were able to distinguish four different ‘obesity phenotypes’ that contribute to being overweight. Three of them relate to energy intake and one to energy expenditure.
Hungry Brain – Abnormal Satiation
Hungry Brain phenotypes don’t feel full in a normal way. Their ‘satiation’ (the number of calories it takes to feel full, by Dr. Acosta’s definition) is off. So, when they sit down to eat, they don’t stop till well after everyone else has had enough. They’re the ones going back for more and more servings at a buffet. In fact, in Dr. Acosta’s study, this group consumed 62% more calories before reaching fullness.
Hungry Gut – Abnormal Satiety
Dr. Acosta defines satiety as how long you feel full for (as opposed to satiation, how much food it takes to make you feel full). If you have a meal and stop eating because you feel full, but an hour or two later you want to eat a whole lot more, then you have the Hungry Gut phenotype, that is, abnormal satiety. You’re the one who joins your friend for a coffee two hours after lunch but want to eat the bag of cookies with it while watching her eat just one of them. Your stomach is the culprit: it’s emptying too quickly, which means one of the main messages to stop (slowing stomach emptying) is lacking. The people with the Hungry Gut phenotype emptied their stomachs 31% faster in Dr. Acosta’s study.
Emotional Hunger – Hedonic Eating
It’s not uncommon to be an ‘emotional eater’—someone who turns to food to get through the stresses of life or to reward themselves—judging by the number of online articles about conquering emotional eating. Dr. Acosta’s group used questionnaires related to anxiety and depression, eating and behavior to gauge if someone had the Emotional Hunger phenotype. This group had almost 3 times higher levels of anxiety as well as increased symptoms of depression and lower levels of self-esteem and body image.
Slow Burn - Energy Expenditure
The fourth phenotype is related to energy expenditure. These are people who seem to gain weight even if they eat the same number of calories as their slimmer friends. Obese participants with this phenotype demonstrated 12% lower resting energy expenditure, were less frequently active, less likely to do structured exercise and if they did, performed it for less time. Not surprisingly, this group had lower muscle mass.
Overall, 85% of the 450 participants fit into at least one of these 4 phenotypes. The most common one was Hungry Gut, but 27% of people slotted into more than one phenotype (Figure 1). In fact, 9% met the criteria for all 4 phenotypes!
Figure 1: Distribution of obesity phenotypes in 450 patients with obesity.1
