so if the metabolism is slowed, how does that impact the energy deficit? does it mean less calories are “needed”? because that could work out, stating probably too simply, that if less energy is being used then there is more excess to store as fat.
and if fat growth is happening despite restriction, is catabolization happening?
(sorry if you cant answer these)
“so if the metabolism is slowed, how does that impact the energy deficit? does it mean less calories are “needed”?
Weight loss is often framed that way: Oh, your metabolism is slowed, so you don’t *need* as many calories as other people need! Just keep eating less and you will maintain your smaller body!
But maintaining your body in a state of suppressed matabolism is not a good thing. It literally means that your body has instituted emergency measures to survive. Any non-essential physiological processes – like the reproductive system – are dramatically slowed and can be stopped completely. And even essential bodily processes like the transmission of fluids into and out of cells (the most basic biological function), to the regeneration of cells, to the functioning of the immune system, to the re-myelenation of nerves (essential for their function) are all slowed down.
This is literally what it means when the sources I linked above say that the basal metabolic rate is slowed by weight loss: The body is slowing down all of its essential, life-sustaining physiological processes in order to survive. That is not a good thing. It is not a state that any organism can or should sustain in the longterm.
PS: And yes, when those basic processes are slowed, it can “free up” energy to grow the fat organ.
Reblogging for the person who was asking what happens when you eat less than your body requires to thrive. Basically, you destroy your body. Don’t do it.
This is how the body defends its own, unique, set point weight.
This is a good blog post on The Eating Disorder Institute (formerly Your Eatopia) about the topic: “ Gaining Weight Despite Calorie Restriction ” The author includes many scientific sources.
In general, though, your confusion comes from the over-simplified myths about weight that permeate our culture.
First, fat is not only an energy storage device, it is also an important endocrine organ. This means that the fat organ regulates hormones, and thus, helps to regulate the functioning of many other organ systems in the body. So the fat organ can grow in response to non-food-related factors, like chronic stress or sleep deprivation, as part of the body’s adaptive response to those factors. (And guess what is stressful? Dieting and weight loss.)
Second, when people do not consume enough energy to meet their needs, two biological processes are triggered. The first is catabolism, which is the process of breaking down the body’s cells to release the energy and nutrients stored in those cells. That energy is then used to fuel the body. This is what people usually think happens when people restrict their food intake to lose weight: the body breaks down fat for energy. Of course, when catabolism does happen, fat calls are not the only cells that are broken down: the body also breaks down muscles, organs, bones, and ligaments to access necessary nutrients and energy. (Yikes.)
But the second process that is triggered by an energy deficit is metabolic suppression: The body slows down all the basic, life sustaining processes of the body to conserve energy.
Losing approximately 10% of your body weight initially slows these life sustaining processes by approximately 15%. And people continue to restrict their energy intake, over time, these life sustaining processes can slow by as much as 30%. Metabolic suppression can also become more reactive over time and repeated bouts of starvation (aka “dieting”). So someone who has dieted in the past will have a metabolism that slows more quickly and more dramatically in response to food restriction compared to someone who has never dieted.
So a person can gain weight while restrictive dieting because an energy deficit causes the body to slow all the life sustaining processes of the body in favour of growing the fat organ, which helps the body to survive in times of stress.
This is some serious shit, people, and it’s a big part of the reason that intentional weight loss through restrictive dieting is so unhealthy.