In my new blog series ' Recovery in the 21st century', I'll be looking at all aspects of recovery in terms of the newest research, science and perspectives, from the actual phases in the process of recovery, to the cognitive and psychological aspects along the way, and also the commonly associated conditions like perfectionism, anxiety, self-harm and depression. I thought I would jump straight in with set point theory- what actually is set point, what determines it, and how will you know when you've reached it.
First of all, your set point is a range, not a specific number. This is the weight range you will be in when you're done. It stays stable within this range without any eating disordered food or exercise behaviours and supports your optimal health, energy and function.
Like most people with an ED the idea of set point scared me. If I let myself start to eat again, if I took my foot off the brake, I was just going to keep increasing to this mysterious set point that I had no control over: so what does actually determine our set point?,
Our bodies are systems and there are multiple factors involved in each area of functioning. So there are a number of factors involved in deciding our set point range.
GENETICS
The major determinant of body weight is genetic.
Our understanding that there is a fundamental genetic basis for your set point is supported by twin and adoptee studies which show that adopted children's weight is more closely correlated with their biologic parents' weight than to their adoptive parents' weight, and that twins show a much stronger correlation in body weight to an identical twin than to a fraternal twin or other siblings (1) . These studies and others indicate that the heritability (proportion of a trait that is determined by genetics) of BMI could explain up to 40-75% of an individual's body weight (2)
Set point theory asserts that a genetically based control mechanism regulates metabolism so that weight is maintained at a genetically-predetermined level despite variability in energy balance.
So, the evolutionary purpose of the set point is to protect against life threatening weight loss in times of famine.
The regulation of metabolism by a genetically based control mechanism also why weight can remain stable with very low caloric intakes and for why underweight people in recovery tend to return to their pre-ed BMI for their age percentile.
METABOLISM
Metabolic efficiency, (which is a term I much prefer to use over 'metabolic rate'), is related to set point.
Survival in primitive conditions favours metabolically efficient individuals who have high set points and therefore, are able to maintain body weight on relatively low caloric intake and this trait is genetically determined. it was an evolutionary asset, as metabolically efficient individuals are more likely to survive in times of unreliable food supplies (3)
The people who have this positive evolutionary trait are prone to gain weight during positive energy balance and not likely to lose weight during negative energy balance (4). Metabolic efficiency also explains why individuals with similar energy intakes and outputs can maintain significantly different body weights. There are too many factors involved to make an accurate prediction about the efficiency of an individual metabolism, which is a good thing in recovery.
MUSCULARITY, GENDER AND ETHNICITY
Muscularity, gender and ethnicity also play into why set point varies between individuals, and particularly between genders. In general, (obviously with exceptions), men are more muscular and tend to be taller than women, with denser bones and bigger and heavier frames. Athletes of both genders are more muscular than average.
Studies illustrate some general differences between ethnicities in terms of body frames and these are also known have an impact on set points.(5)
MENOPAUSE
Menopause is another factor to consider in determining set point and often overlooked because of the lack of understanding and awareness of eating disorders in adults. Menopause is associated with increases in weight, fat mass and waist circumference along with decreases in skeletal muscle mass and metabolic efficiency(6).This is thought to be highly adaptive (7) and associated with a three-fold drop in mortality(8). The set point can be expected to increase up to 20lbs (9.07 kgs) during the menopausal transition.
HOW DO I KNOW WHEN I'VE REACHED SET POINT?
For adults, your set point weight will be stable (within range) and resistant to change, despite variations in daily intake and caloric expenditure. Another sign of reaching your set point is you won't be freaked out about the idea of a set point anymore,or not being the skinniest in the room anymore. This weight restoration will in itself create a considerable improvement in obsessions and preoccupations with food, shape and/or weight (9)
Indications that you're nearing your set point, along with weight stability, include normalised bloods (such as testosterone, oestradiol, IGF-1 and cortisol levels), not feeling cold all the time and no dizziness upon standing (10).In adolescents and young adults, achieving set point is associated with stopping bone loss and possibly some bone density recovery (11)
The return of periods is another sign that you've reached your set point, (or overshoot-which I will cover in another post in this series). Menstruation, as a non-necessity for fundamental survival, is commonly 'switched off' when we enter a time of starvation; secondary amenorrhea (the absence of three consecutive periods), may happen at normal and higher weights when weight loss is sudden, (12),or when caloric deficit from excessive exercise and/or severe restriction, leaves too little energy for the body to maintain regular periods.
In men, the return of normal testosterone is an important indicator of reaching set point.
It is perfectly natural, especially as you're navigating the early phases of recovery, to want to know what weight you will be when you've recovered; It's also normal to want the reassurance of having a goal weight, or knowing if there's an ideal, 'best' weight for you. Ultimately, your best weight can be thought of as your genetically predetermined natural weight,(13), or, the weight your body will be at when you are no longer engaged in disordered eating behaviours or compulsive exercise, when you feel healthy again, you will have energy again, you will be able to think about things other than food, and by then, well, your weight won't feel like such a big deal.
(1)(Hainer, Stunkard, Kunesova, Pariskova, Stich and Allison, 2001; Stunkard, Foch, and Hrubec, 1986; Stunkard at al, 1986)
(2)(O'Rahilly and Farooqi, 2008; Schousboe et al, 2004)
(3)(Dokken and Tsao 2007)
(4)(Muller, Bosy-Westphal and Heymsfield 2010)
(5)(WHO Expert Consultation, 2004) (Boykin, Diez-Roux, Carnethon, Shrager, Ni, and Whitt-Glover, 2011)
(6)(Soni, Conroy, Mackey and Kuller, 2011)
(7)(Freeman,Sammel,Lin and Gracia, 2010)
(8)(Macdonald, New, Campbell and Reid 2003)
(8)(Singh, Haddad, Knutsen, and Fraser 2001)
(9)(Golden, Jacobson, Sterling and Hertz 2008)
(10)(Tyson, 2010)
(11)(Mehler,Sabel,Watson and Anderson, 2008)
(12)(Genazzani, Riccieri, Lanzoni, Strucchi and Jasonni, 2006)
(13)(Herrin, 2003)