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The body’s response to adequate fuel in anorexia

The body’s response to adequate fuel in anorexia

By Jaimie Winkler, RD, LDN and David Alperovitz, Psy.D.FullSizeRender-2 headshot best

Research on the refeeding process provides us with parameters regarding resting metabolic rate, body composition, and hormone composition as someone restores weight.  This knowledge can provide comfort to those in physical and psychological pain during refeeding. The degree and amount of knowledge people are given during this process is important as individuals have different preferences for how involved they want to be in knowing the specifics of their treatment.  There are indications that for some individuals too much information about the refeeding process can provoke more social comparisons, a greater need for reassurance, negative self-evaluation (for not meeting the standard), and can fuel the sufferer’s intolerance for uncertainty and discomfort. The core symptoms of an eating disorder consist of: fear of weight gain (fullness, fatness, or discomfort), fear of uncertainty, desire for predictability, a need for reassurance, discomfort, and avoidance. All of these symptoms need to be addressed with skill development as well as information.

Science and clinical experience both reveal that the refeeding process may be uniquely painful for each individual – independent of weight. Refeeding can be as physically and psychologically uncomfortable for someone who is overweight, as it can be for someone of average weight, or for someone who is underweight.  This article speaks to the weight gain process. Even those not on formal weight gain plans may recognize themselves in this description. 

The timeline we provide is drawn from a compilation of clinical experience and is supported by research studies that address singular parts of this complicated process. To understand what happens during refueling, we first we need to look at what happens during the malnutrition process. The key things to know are:

  1. Energy Reallocation. This is the “metabolic rate decreases” fact that scares many people. Let’s call it what it is: when there is not enough energy to properly run the body, energy gets allocated from less important processes and structures to the most important ones. Energy is delivered to muscles, organs, and tissues only as they relate to surviving, not toward optimal function. At this stage you may not realize just how poorly you are functioning until you have adequate energy and are able to compare the difference. 
  2. Increased Interest/ the “pull” toward food. Whenever you avoid food, you are more drawn to it. It is important to differentiate interest in food from actually enjoying food.  Interest often translates to the experience of seeing food everywhere, noticing when others are eating, and worries that if you start eating you will never stop. When this occurs, social interests, intellectual pursuits, and life enjoyment typically take a backseat to food. 
  3. Emotional Insufficiency. When food is the primary objective of each day, the helpful emotions that guide you through social interactions and safety situations are frequently absent. Some people prefer to turn their emotions off or “numb out” by restricting food. This process can be both conscious and unconscious.  It is important to note that the process of restriction suppresses both positive and negative emotions equally. We have come to know that emotions can be seen as critical data for navigating the world and making decisions.  With limited access to emotions one becomes significantly handicapped in navigating life.

Phase 1:  Immediate Changes: Going against the current


Immediately upon eating more your body relishes the extra energy and quickly begins to put this energy to work. Metabolic rate (calorie using capacity) rises as you provide adequate nourishment. Calories are the trigger to an increase in metabolic rate. 

The serious risks associated with “refeeding syndrome” are directly related to the way that the body immediately starts to make more energy when it doesn’t have enough nutrients to meet demand. The consequences of refeeding syndrome, which is different from the refeeding process, can range from low lab values to mild edema to heart failure.  

When in a state of malnourishment, hormone levels that regulate tissue growth are decreased and cells become resistant to their effects. The net result is that more glucose becomes available for vital organs and vital movement. A malnourished body assumes that this movement is aimed toward getting food to eat – not with the goal of exercising or burning more calories. Your arms and legs can still carry you to a job, class, or an appointment because energy has been allocated to those limbs to get them to work for hunting and gathering food. The fact that these activities are possible may have you think that things are OK.  Nothing could be further from the truth.  Survival mode must be differentiated from “OK.”

The same hormones that contribute to building lean body mass and body fat remain ineffective when you begin eating more. At this point, energy and nutrients are primarily directed toward restoring function to vital organs.

The first step is for the body to gain water weight to achieve normal hydration. Here the body is moving from a dehydrated state to a hydrated state. This can occur suddenly and can be severely uncomfortable because the change is immediate. For instance, you can gain several pounds of “water weight” overnight because you drink several pounds of fluid in a day to stay adequately hydrated. The same does not hold true with food, you cannot gain several pounds of body weight overnight because much of the food eaten gets converted to energy and leaves the body via heat, energy, carbon dioxide, or water (through the nose, sweat, or urine). 

Dehydration occurs for many reasons: laxative or diuretic abuse; decreased intake of glucose, protein, and electrolytes; refusal to drink water; as well as excess consumption of protein or caffeine intake. 

A danger here is that one of the eating disorder’s core beliefs/fears will appear confirmed: That you cannot eat normally without “blowing up.”  However, weight gain is not and should not be seen as a maladaptive response to food.  Weight gain is a normative process and the body’s logical and correct response to the reintroduction of food that the eating disorder sought to avoid. 


Restrictive eating patterns can cause abdominal pain and bloating. Important daily maintenance to the body’s intestines is sacrificed when intake is restricted. Many repairs are often needed before the system begins to work optimally. Low caloric intake slows down and delays the emptying of stomach contents leading to nausea, slow digestion, and constipation. Both restrictive eating and low caloric intake can leave you feeling fuller with less food. It is both normal to begin to feel hungry or to feel excessively full at this point. Hunger may become obvious once your body starts using and requesting more energy. However, depression, stress, and anxiety can still be potent appetite suppressants even as your body demands food.


When you begin to eat more there is no way to direct the allocation of energy to a specific body system. This initial period of refeeding often is associated with a feeling of “wrongness” that you are not listening to body cues. The eating disorder logic/fear of “once it starts it will never stop” can be present, in an attempt to thwart recovery. Individuals often have the experience of fearing that each new uncomfortable physical symptom will never cease. It follows that this occurrence is often filled with high anxiety and can be one of the most fearful moments of the entire recovery process. 

Phase 2: No solid ground


During the weight gain phase of refeeding, three types of weight gain occur: continued restoration of normal fluid balance, lean body mass gain, and body fat gain. Research studies consistently demonstrate that weight gain from body fat is only part of the equation. To create new body fat there must be an excess of calories. Each day during weight gain, important and small amounts of lean body mass and body fat gain are being created.  Simultaneously, daily fluid shifts of between 1 to 5 pounds are occurring. It is impossible to know which aspect of weight is increasing on any given day. This is an important area to practice tolerating the discomfort associated with uncertainty.  Variations in fluid weight can be more pronounced during the weight gain process.  Fluid fluctuations relate to daily sodium and carbohydrate intake, the amount of fluid necessary to excrete the byproducts of repair through urine, as well as fluid retention to support tissue growth.


During the weight gain phase, individual appetite experiences can vary dramatically. Some report prolonged “fullness” and lack of appetite. Fullness often can get confused with gas or bloating. Increased gas production occurs for many reasons connected to food production and healing. Many report wild swings between insatiable hunger and profound fullness. Some may experience both ends of the hunger spectrum in a course of an hour. Hunger signals are unpredictable and intense. Even on very high calorie meal plans designed for weight gain, people report hunger. In the famous Ancel Keys Starvation Study, subjects were eating up to 6,000 calories per day and still felt hungry or unsatisfied. 


Eating disorder thoughts and beliefs use the chaos and unpredictability of this phase to lure you back to the disorder. People often spend countless hours worrying about the characteristics of weight gain. Some dive into eating disorder behaviors simply as a way to cope. Even within a 24-hour treatment setting, it is possible to use eating disorder “rules” regarding amounts and types of food to develop a sense of “safety” or in order to slow down the weight gain process. Others create rules to apply to the weight gain experience, choosing high calorie foods to speed the process or favoring desserts that are no longer off-limits. The least eating disordered responses to this phase are to choose foods you like, challenge the fears about particular foods, and always strive to refrain from controlling the process. Way too much brain space can get devoted to the “what ifs” when a fear of uncertainty prevails.  Being open to information from clinicians about the refeeding process can also help one put things into context and simultaneously be reassuring that discomfort is expected. Tolerating the uncertainty thus becomes a critically important recovery tool. 

Phase 3: A light at the end of the tunnel?


Many worry about developing a “refeeding belly.” A clinical definition for a refeeding belly does not exist.   Many often worry that they will look pregnant or have an abdominal circumference above a “normal” or tolerable level. Sometimes it is impossible to avoid abdominal discomfort. Following a normal sized meal, you can often feel a tightening in your pants as the abdomen expands to accommodate food just eaten. With meal plans designed for weight gain, this experience is often increased. Additionally, extra stool or urine is produced from the break down of food and conversion to energy thereby creating more mass in the intestines. 

Research indicates that weight gain will often occur first in the abdomen before it does in the legs and arms. This adaptive process occurs in order for body fat to protect and separate vital organs. Due to initial weight gain in the abdomen, one can have the experience of feeling “disproportionate” because the arms and legs have yet to catch up. In research studies, the difference between the abdominal circumferences of someone who has recently restored weight versus an age/weight/height-matched control can be just a pants size in either direction. One year out from weight restoration there is no statistical difference between the shapes of weight-restored individuals and those who have never had an eating disorder. True presentations of a late-stage-pregnancy looking abdomen are very rare. Factors that reduce the risk of disproportionate abdominal weight gain include: regular periods or shorter duration of amenorrhea (less than 1 year), early intervention, and relapse prevention. 


Toward the end of the weight gain phase individuals on a high calorie meal plan (e.g. >3,500 calories per day), may experience fewer episodes of hunger and feel full before even starting to eat. Again, this is both an adaptive and natural response to overfeeding.  The body in a sense establishes a checkpoint from the hormone systems that regulate appetite and body weight. This often can be even more pronounced in a 24-hour treatment setting where food amounts are consistent and higher calorie than in outpatient treatment. Experiencing a change in appetite can contradict the notion that your body is “broken” and doesn’t know how to maintain an appropriate weight. 

In outpatient settings, weight gain might slow a bit as one approaches a healthy weight. It is important to distinguish that a healthy weight is differently defined (based on several factors) for each individual, and is not simply a BMI of 18.5kg/m2. In fact, more than 85% of women recovering from an eating disorder need to be at a BMI of 20kg/m2 or higher for full body function and normal appetite cues to be present. Individuals who have been discharged from a program at a BMI below 20kg/m2 and told they can maintain that weight, often find that their bodies may have different ideas. This should not be seen as the body “tricking” one into gaining weight. More accurately what is occurring is that one is trying to “trick” the body into maintaining a low weight. 


Nearing the end of weight gain can come as a relief or feel like a loss.  People approaching this stage often report feeling sad (or even angry) that the “food party” is over. Often overlooked is the fact that many people recovering from eating disorders actually enjoy food. At this stage, normal amounts of food may appear small. As one continues with recovery, this normalizes. 

Many people report feeling great relief as they approach or achieve a healthy weight. Rarely is it as bad as they expected it to be. The eating disorder feeds on inflated fears of the unknown. Body image will vary dramatically because this is a major transition point in treatment.  The uncertainty of life is reflected in this unstable body image. Often people report feeling like they should be “done” with treatment at this point, but in many ways the process has only just begun. (Hence the question mark in the title of this section – Light at the end of the tunnel?)  

Phase 4: Into the great wide open


When an individual is at a healthy weight and has adjusted his/her intake to support maintaining that weight, he/she sometimes prematurely assumes that the physical healing process is over. Research suggests that it can actually take up to 12 months for the body to fully heal from malnutrition. At this point, the majority of work to restore hydration is complete.  Although you have created lean body mass, you may not look “toned” (an eating disorder euphemism for looking “thin” or “good”).  Remember by about one year out, there is no difference in shape between a weight-restored body and someone who has never had an eating disorder. Most people report a “redistribution” of weight within six months, although many report they begin to feel more comfortable within a few weeks. It should be noted that the lean body mass created or repaired makes up essential skeletal muscles for basic movements and not those for athletic performance. Lean body mass also includes increases to organ tissue. 

Because physical restoration isn’t complete, metabolic rate can stay elevated for many months. People often continue to count calories or compare their intake to others but it is never a fair comparison. At this juncture one will need more food than if they were the same weight, height, and age but never had an eating disorder. For example, a 150-pound woman may need 2,700 to 4,000 cal./day to maintain full body function and weight after weight restoration.  You could maintain weight on fewer calories but this would involve starting to sacrifice critical functions like digestion, reproduction, and heart strength, as well as stunting physical and psychological recovery.


Hunger cues still might not make sense. Many people want to quickly jump to intuitive eating and abandon their meal plan. Reaching a healthy weight is not the end of the process. It is important to continue to follow a basic meal plan and work with a team on incorporating information about hunger and fullness cues. You should always add if you are physically hungry, because metabolic rate remains elevated for up to 1 year. You can work on distinguishing physical and psychological hunger but know that one should always err on the side of a little more than a little less. Clinicians advocate for seeing how much food one can eat and maintain weight, not how little one needs. The only “false hungers” people experience tend to be medication related, so talking to prescribing providers becomes important if there are doubts around trusting physical hunger.  

Feeling physically full or overfull at times is not a failure. The weight gain process has provided knowledge about what it takes to genuinely gain weight over time. Having a day of fullness or fullness after a meal does not translate to weight gain. The major goal of this phase of recovery is to reduce the intensity of your response to fullness, perceived weight gain, actual weight gain, and concerns about hunger. Learning to make small adjustments with good intention becomes important when you think you have had too much or too little food. This is always a delicate balance as the eating disorder can often lead one to overcorrect either by restricting or binging, as well as overestimating and underestimating. 

Ultimately having consistent hunger and fullness cues help break the myth that being hungry is associated with weight loss and being full is associated with weight gain.  


Physical experience often continues to be variable. Each day can feel like you are turning away from your identity. Choices can seem counterintuitive, although you intuitively know you have been able to feed yourself at times before in life. You often long to be “normal” and at the same time mourn the loss of a sense of self. Even as others see your body as healthy and your eating pattern as adequate, you will still fight thoughts and urges daily. Even the men in the Ancel Keys’ starvation study took about 6 months after restoring weight and intake to begin to “feel normal” about food. Putting one’s cognitive and emotional experiences into words is a critical starting point for validation from others as well as crucial in preventing a return to a focus on body or behaviors to express distress. 

Recovery happens one small choice at a time. You redefine “good” and “bad” days. You repair one cell at a time. Slowly the thoughts recede because you stop responding to them. There are brief moments of reprieve. You string together longer stretches of hope and freedom from the burden of the eating disorder. Just like no one can tell you the exact day your body recovers, no one knows exactly when your mind recovers. In both arenas, the cues for recovery are subtle and often uncelebrated because they seem to happen in the most uncomfortable ways.  

About the authors – 

Jaimie Winkler, RD, LDN

Jaimie earned her degree in nutrition from West Chester University in Pennsylvania and completed her dietetic internship at Brigham and Women’s Hospital in Boston.  She also holds a degree in history and journalism from the University of Michigan. Jaimie has been with the Klarman Eating Disorder Center at McLean Hospital in Belmont, Mass., for 8 years. She has provided outpatient nutrition services for those struggling with eating disorders or medical issues since.  She has led groups on healthy eating in schools, outpatient eating disorder groups, lectured in the Boston University nursing program, helped develop hospital food programs, and spoken with high school sports teams about appropriate fueling.

David Alperovitz, Psy.D.

Dr. Alperovitz earned his Doctorate in Clinical Psychology from the Massachusetts School of Professional Psychology. He completed pre-doctoral training at Tufts University and a Post Doctoral Fellowship in Psychology for the treatment of Trauma and Dissociative Disorders at McLean Hospital and a Clinical Fellowship in the Department of Psychiatry of Harvard Medical School. Dr. Alperovitz holds an appointment as an instructor in Psychology at Harvard Medical School. He has over 20 years experience working at McLean Hospital primarily with individuals with eating disorders, trauma histories and dissociative symptoms. Dr. Alperovitz has maintained a private practice treating adolescents and adults for over 15 years. Dr. Alperovitz has worked for the last 5 years at Klarman Eating Disorders Center at McLean Hospital.




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