How low can we go?
Calories Part 2
Suspension of disbelief is something generally reserved for works of fiction. When we watch movies or read books we sometimes have to ignore logical thinking and reality in order to enjoy those works. In the movie Interstellar there were some errors in the physics particularly in relation to time. In order to enjoy the film we have to put those errors aside. If you read part one you will most likely have to do a similar thing when reading further about calories.
For now let’s pretend we don’t know we burn our food or what a bomb calorimeter is. We can do this because even if that measurement is inaccurate, and it is, we can still examine the efficacy of quantity measurement a weight loss tool.
Over the next few posts we will explore the notion that in order to lose weight we need to eat less and burn more. We will start with the practical. Do we have the ability to make this work now. In later posts we will explore the theoretical. If we eat less and move more will we lose weight.
Practical Calories One: How low can we go?
From a practical perspective the first thing we need to know is how low we can go. How much of a deficit can we function in? This question is crucial. The lower we can comfortably go the less reliable our measurements needs to be. Let me explain. Let’s assume I eat about 3000 calories a day. I want to create a deficit. Comfortably being able to sustain myself on 1500 calories gives me a larger margin of error than say 2000.
One of the best resources to get an answer dates back all the way to the Second World War. In late 1944, during the waning days of world war II scientists, led by Ancel Keys of Diet Heart fame, enlisted 36 male conscientious objectors to voluntarily restrict their caloric intake. The Minnesota Starvation Study as it is known began with a 12 week control diet of 3200 calories and then 24 weeks of restriction that included just 1570 calories.
During the restriction phase the subjects mental state started to change. The researchers found increased incidence of depression, hypochondria and hysteria. Sexual desire along with cognitive function was reduced. Everything not food related lost meaning. Even the men’s relationship to food changed.
"They would coddle [the food] like a baby or handle it and look over it as they would some gold. They played with it like kids making mud pies," wrote one of subject. They would lick plates, diluted potatoes with water and anything else they could think of to make themselves feel full.
A diet that changes your relationship to food and causes “apathy among the subjects, punctuated by paradoxical periods of irrational irritability” does not sound like something doable in the real world. While the subjects were healthy weight to begin with this lack of adherence seems to very low calorie diets seems to extend even to overweight and obese individuals.
One study even found that adherence was negatively correlated with the amount of caloric restriction. Study after study find adherence is key. This really shouldn’t come as a surprise. You can have the most effective solution but if everyone quits it doesn’t work. A plan that comes with side effects like depression and hysteria may not be the easiest one to stick to.
In the Minnesota Starvation Study calories were halved and that clearly was too drastic. So what is a more reasonable number? Most of the latest studies exploring long term caloric restriction are done between 20-30% of weight maintenance. These are again done in controlled environments which most likely result in far better adherence. These studies though were run for 6-12 months so it likely that these were at least close to the low range of comfortable caloric restriction.
If we use these percentages though we can assume that someone currently maintaining on 3000 calories (the average American eats about 3700kcal) they could cut their calories to around 2100 – 2400kcal. This seems much more doable than the severe restriction used in the Minnesota Starvation Study. Even at the low end 2100kcal seems more bearable than 1500kcal.
Apparently, some of the major diet systems disagree. Diets like Nutra system run as low as 1000 calories a day for the first week and then level out at 1500 or so calories a day. Jenny Craig gets as low as 1200 calories. Remember our conscientious objectors went crazy on 1570kcal.
It is not hard to see why dieting is near impossible. Most diets feature calorie levels below the starvation study which raises the question why are these plans so low? There are two practical reasons (there is also a theoretical one but we will ignore that for now). First conventional wisdoms says a big deficit would lead to faster weight loss which would help with adherence. It is easier to stick to a plan when you see results. The second scenario we will explore in the next two posts and comes from a lack of being able to accurately measure calories.