Losing Weight

For each day over more than a month I tracked my weight and food energy in an effort to empirically discover the basis of a strategy for achieving my ideal weight.

I found that weight in pounds, measured right after waking up, is proportional to the calories consumed the day before, with the calories per pound randomly distributed around almost exactly 10 (with repeatability, measured as the standard deviation, of 1.4). Some research into how many calories are used with varying kinds of exercise showed that this relationship tracks closely with the energy spent on a full day of sleep as a function of weight.

This made the strategy simple: daily consume only the amount of calories needed to maintain my ideal weight, calculated by multiplying 10 by that weight. To improve my chances of not exceeding that weight, I wouldn't consume any more than that; and to avoid getting too much underweight, I would consume no less than 8.6 (10 minus 1.4) times the weight.

I couldn't help but compare what I was learning about myself with what I had learned about consumption of resources by humanity as a whole. The calories needed to maintain ideal weight seemed to correspond to what I had derived as the "minimum ecological footprint," the amount of resources provided by other species that is required for stable basic survival where the resources are reliably available (as became the case globally, on average, about fifteen hundred years ago). The lower value of calories I was aiming for corresponded to the footprint for a hungry state of being, with uncertain availability of resources, which I had calculated as 80% of the "minimum" and was the starting point for idealized groups of people driving historical population and consumption change since the start of civilization.

It is tempting to try making a comparison between being overweight and consuming more resources than is healthy for the world. As we are able to consume more stuff besides food, we are also able to consume more food. Our life expectancy, which tracks with footprint much like happiness (gaining less and less as we consume more), begins to decrease as we become more overweight, implying that doing so overwhelms our inner ecosystem just as increasing our footprint eventually overwhelms the external ecosystems that support us. I have long hypothesized that there is an upper limit to happiness, beyond which we cannot go without self-destructing, and it's not a great stretch to expect that obesity might have a role in this given that heart disease is the top killer in the affluent U.S.

My personal motivation for losing weight is tied to the health risks of not doing so, just as my motivation for downsizing is tied to my awareness of how consuming more stuff is contributing to global extinction. It amounts to a selection of personal limits, much as half of the idealized groups in my reconstruction of world history (one-sixth of the population) chose to consume only one-fourth of the renewable resources available in a healthy world while the other groups chose to consume everything.

I am a latecomer to all of this. Many others have experienced a similar awakening of a desire to live within healthy limits, with common reaction to growing evidence of the alternative's imminent failure. Although we are far beyond the ability to succeed on a global scale, I share the goal to nurture that desire as much as possible, for as long as possible, and with as many people as might choose to share in it.

The Longevity Trap

A new set of simulations involving happiness, longevity, and population shows that when different isolated groups join together to form a larger, competitive group, population may be traded for longevity except when growth rate is the only difference.

Recall that longevity is the time it takes for a group to begin disabling the habitability of its environment by consuming species that keep alive the species it directly depends upon for survival, and that my calculations show that humanity recently reached that point. The simulations indicate that world history can be approximated by a lot of isolated groups, which is also equivalent to what would happen if isolated groups came together and allocated resources equally among them. If the world instead had competition among its subgroups for resources, then the average population over history would be smaller (such as 50%), and longevity would be longer by the same fraction (150%); happiness would have dropped only slightly (3%).

In general, any differences between isolated groups in population or per-capital consumption of ecological resources (footprint) will translate into differences in power to acquire resources and convert them into personalized environments. Those power differences will result in a loss of population when the groups are merged and they must compete for resources with too few available for some people to survive when the resources are allocated according to power. Having fewer total people enables those who are left to consume resources for longer at their current rates, thus increasing longevity. This is not the only way to increase longevity, though: by decreasing consumption rates, longevity can be increased without an accompanying drop in population.

Ironically, any growth at all ensures that a group's longevity will eventually reach zero. Pursuing more longevity, while insisting on growth, is therefore a trap. Even if we use the increased longevity to find more resources so we can accommodate more people, we will be forced to adjust and eventually limit the growth rate of consumption based on physical constraints of speed and availability of resources. To pursue more longevity and accept loss of life as its cost is to automatically assume that the casualties have less value than the survivors or their potential replacements.

Discontinuity

Last week I thought of a more general form of the relationship between population and the consumption of resources. Preliminary testing suggests that it's much more robust than previous versions of my population-consumption model.

You may recall that I had identified what I called “transactions” as the only mechanism determining how much mass people will convert into waste each year. People extract resources from wherever they are, process them into useful forms, and exchange the results with other people. If everyone in a population conducts one transaction per year with everyone else in the population, the total number of such transactions is one-half the square of the total number of people. The average mass for each such transaction is what I call the “transaction mass.” With transactions accounting for all consumption, transaction mass included both the mass of stuff exchanged and whatever was used to do the exchange (such as fuel used in transportation).

In the new version of the model, I've redefined transaction mass as only the average amount used to perform an exchange. The majority of the total consumption is what is actually consumed by people. Each person in the population, on average, consumes an amount of mass which I call “extraction mass” (because in the simplest case each person could extract resources on their own). Total consumption is the sum of the transaction mass and the extraction mass, and per capita consumption as a function of population ends up being a straight line.

When I was assuming that total consumption varied with the square of the population in an isolated population like the Earth, all that was required to determine how it changed over time was a set of historical population numbers and a value for consumption at some point in time. As a proxy for consumption, I used the global ecological footprint, which measures the per capita ecological impact of humanity on a global scale, and the starting value was assumed to be the minimum reported for countries in 2006. I then did an elaborate curve fit of consumption, constrained so that when projected to the present, it matched the most recent measured value. Projecting consumption into the future showed that it would peak and then drop; and since it was interdependent on population, population would likewise peak and crash.

The new version of the model was inspired by an attempt to simply describe and justify the elements of the previous one, including some inconsistencies with current data that couldn't be easily explained. Specifically, recent estimates of ecological footprint show very little change over the past fifty years; and per capita world energy consumption shows the same pattern, even though population more than doubled over the same period. In contrast, the previous version of my model shows a steep change in the equivalent per capita consumption. If the trend of the data was consistent over all time, early civilization should have been consuming almost as much as we are today, and living just as long, which was clearly wrong. It was natural to assume that the flatness of the data was a historical fluke, but as I was testing my assumptions, I realized that such an explanation was unsatisfactory. Unfortunately, even with the new version the problem remained.

Then I realized that I had a way to measure per capita consumption going back much further in time than the footprint and energy data. In addition to historical estimates of population, there are also estimates of life expectancy, and I've known for a while how life expectancy and footprint are empirically related. I could therefore use life expectancy as a way of calculating footprint, just as I have used it to convert my projections of footprint into life expectancy (and, similarly, happiness).

The results were astonishing. For one thing, ten thousand years ago, the ecological footprint was one-fifth of my previous estimate of the minimum footprint. The transaction and extraction masses stayed effectively constant right until the middle of the last century. From 1950 until 1960 (the decade I was born), the transaction mass jumped by a factor of nearly 30, and then stopped changing; meanwhile, the transaction mass remained what it had always been. The footprint (and presumably all per capita consumption) looked just like a mathematical “step function,” corresponding to an almost doubling of life expectancy. The reasons for this near-discontinuity in the historical trend likely involve a combination of major advances in medicine (such as the development of antibiotics) and the widespread availability of fossil fuels and oil derivatives for nearly every purpose, not the least of which being the creation of artificial fertilizers that could immensely increase food production.

Perhaps the most important prediction of the previous version of my model was the impending crash of the world's population. I have so far been unable to find evidence for such a crash in the new version. The closest I can come to justifying such an expectation now is the existence of the step function itself, an understanding that the oil that powered it is becoming much harder to get, and the clear evidence that we have exceeded the ecological carrying capacity of the Earth and may soon reach a tipping point in Nature's ability to support us. To the extent that the previous version does an excellent job of curve-fitting population over time, and population is the main variable in the new version, it may yet prove to be accurate in at least that one regard.