This post is part two of three about the Minnesota Starvation Experiment. This was a research experiment carried out during the Second World War that even today provides us with the best research evidence we have about the effects of semi-starvation and 'refeeding' on a person, not just physically but also mentally, behaviourally and emotionally. Part one covers what the experiment involved and some of its key findings. This post relates the study findings to what it is like to have and overcome semi-starvation resulting from a restrictive eating disorder, considering where the similarities lie, as well as the differences.
The information for these posts is also taken from my book, Addicted to Energy Deficit, so if you do want this in book form, alongside a lot more information, then please pick up a copy.
Relating The Minnesota Starvation Experiment to Restrictive Eating Disorders
The findings of the Minnesota Starvation Experiment provide a clear indication of what physical symptoms, behaviours, social and psychological signs and weight changes are common to someone in a semi-starved state and what to expect once free eating resumes.
This information is also critical in informing us about some of the commonly seen signs and symptoms in restrictive eating disorders. It helps us to identify which symptoms people commonly experience might be purely related to the body being in a semi-starved state and what’s related to the eating disorder itself. The experiment also gives us information about what’s to be expected in the process of overcoming a restrictive eating disorder in relation to eating more and gaining weight, including potential time frames for physical restoration.
An initial critical point to note is that the men in the Minnesota Starvation Experiment were semi-starved for six months. In just six months, these men experienced all the physical, psychological, behavioural and emotional difficulties that were described in the first post. Compare this to someone with an eating disorder who has usually been restricting their intake and living in a semi-starved state for much longer. However, just as these men reported a return to full health and normal lives after their return to free eating, so, too, do people who have had restrictive eating disorders for any length of time.
Physical Energy Levels
One of the key study findings in relation to the effect starvation had on the men that differs significantly to people with eating disorders relates to physical energy levels. The study findings reported that the men all became very lethargic, lost their strength and became slower in their movements. None of the men were reported to experience hyperactivity as part of the starvation effects. But in people with restrictive eating disorders, hyperactivity is often a key feature, where many people with eating disorders actually feel more energised and hyperactive when they are in a state of energy deficit. This indicates that the hyperactivity and false sense of energy seen in people with restrictive eating disorders is a more unique symptom of an eating disorder and not a normal response to hunger or starvation. This is where the evolutionary and genetic theories for eating disorders are beneficial as they help to explain this anomaly.. and I will write more about the genetic findings to eating disorders in future, or it is covered in depth in the book!
Binges & Extreme Hunger
The Minnesota Study results clearly demonstrated that semi-starvation can result in binge eating (in which the men reported a loss of control over what or how much they ate). This has also been seen and reported in prisoners of war upon having access to food again. Therefore, people with binge eating as part of their restrictive eating disorder are experiencing a very normal physiological reaction of the body to hunger and starvation. None of these men had eating disorders and their binges stopped after a few weeks or months of being able to eat freely again and restoring their body to energy balance.
Of the men who didn’t experience true binge eating, the majority were still observed to eat high amounts when they could after the semi-starvation period. In the first weeks, intake was estimated for some to be around 11,000 calories a day, and some of the men were still eating high amounts eight months after the study. One man reported that it took three years for his hunger and eating patterns to return to what he considered a more normal level.
Physical Restoration & Weight Gain
The men reported that on average they felt that it took around two years for them to feel physically back to where they had been when they entered the experiment. This demonstrates that even with good food intake over a lengthy time, the body takes time to fully repair and heal from any period of semi-starvation.
The men all gained an excess of fat in the initial weight restoration phase to their fat levels before the experiment. They initially regained on average 10-14 percent more weight than they were at their control weight range, which we can consider their genetic set point weight. Many of the men expressed concern at the gains of fat around their midsection, thighs and buttocks. This is a clear demonstration of what we today consider the overshoot phenomenon. The body needs to initially regain more fat stores in order to carry out the full non-fat mass tissue restoration and repairs that are needed. Once this has been completed, any ongoing excess weight is naturally lost (the science to overshoot is something I will also cover in more detail in future).
Understanding you can be Semi-Starved at any Weight
Today we know that people can be semi-starved and malnourished at any weight or shape if they have lost weight below their genetic set weight range (please see this post). If you have a restrictive eating disorder but you are not at the low end of the BMI spectrum then you may be wondering why the men in this study all reached a weight that would be considered underweight by BMI chart.
All the men selected for the study were of genetically small builds. The average BMI of the men before the study started was 21.9, which even for young, healthy men is low. Even the man with the highest genetic weight at the start only had a BMI of 25.4. They each lost an average 25 percent of their start weight during the experiment, which meant their weight did drop to the lower end of the BMI spectrum. However, the effects of semi-starvation are the same whether you reach a 'low' BMI or you are still in the 'normal' BMI range after weight loss. The information from this study applies equally to those with a restrictive eating disorder in a bigger body as it does smaller ones.
The men in the study who did have slightly higher natural set weights also remained at higher weights as they lost weight. This was something that Keys (the lead researcher of the study) became upset about as he felt they were not losing enough weight. As a result, these men had the most significant cuts in their intake. The symptoms these men in the higher weight range experienced from semi-starvation were as significant as those in the lower range.
Distress from 'Underfeeding' to Nutritionally Rehabilitate
Another noteworthy point from the study is that the men reported that the most challenging time was during the initial rehabilitation phase, when their calories were increased but still restricted. The men reported that this was incredibly hard because their hunger remained so high despite now being given more food. There is a comparison to make here to the use of meal plans for people overcoming eating disorders. When using a meal plan, it can be hard to ensure that the food amounts given on the plan will meet the deep hunger present. For people on a plan who are not getting enough food, just like the men in this study, it can be a very distressing experience. Therefore, meal plans need to be used with care to ensure that they are never restrictive to someone who is experiencing confusing deep levels of hunger while in the process of emerging from a semi-starved state.
Key Differences Between the Study & a Restrictive Eating Disorder
The men in the Minnesota Starvation Study didn’t have restrictive eating disorders. They didn’t develop an addiction to the energy deficit that was caused by the semi-starvation, most likely due to the fact that they didn't have a genetic predisposition to develop an eating disorder. For them, a state of negative energy was intensely uncomfortable from the beginning, and they were desperate to eat again and return their body to a state of energy balance. This is very different for someone with an eating disorder who develops positive reinforcement from their addicted brain as a result of energy deficit.
By the time someone with an eating disorder seeks support and wants to overcome it, they have also usually had the eating disorder with the associated restrictive eating and behaviours for longer than six months. Therefore, the brain circuitry that drives these habits and behaviours has had a significant amount of time to become deeply embedded and reinforced.
Conclusion
The Minnesota Starvation Experiment is incredibly important, and understanding its findings should help you understand some of the symptoms you experience that can be related to being in a semi-starved state. The findings should also reassure you that high hunger, eating beyond physical fullness, binges and potentially gaining more weight in the restoration process than your genetic set weight range is all absolutely normal and necessary physiological reactions.
The men in the Minnesota Starvation Experiment went through a very real and hard process during this experiment and it did change their lives. Perhaps if you have a restrictive eating disorder and you too know how hard hunger can be, then like me, you feel a deep seated empathy and gratitude to these men who did starve so that still today, we can have a greater understanding and insight into just what impact being malnourished and semi-starved alone can have on a person—even before you throw a restrictive eating disorder into the mix.
In the final part of this series on the Minnesota Starvation Experiment, the effects of starvation that were clearly identified by the experiment are covered and how they compare to someone with a restrictive eating disorder.
**For more information on eating disorders and how to overcome one, please don't miss my newly available books,
And,
The information for this post was largely taken from Addicted to Energy Deficit.
If you like to listen, as well as (or instead of read!) then this blog post is the transcript of a podcast episode which you will find on my podcast series,
available on this website, all mainstream podcast platforms and on YouTube.