In the classic Monty Python 1970s movie, The Life of Brian, Brian tells the swarming masses, “You are all individuals,” to which the group responds as one, “Yes, we are all individuals.”

The fact is, we are all individuals and respond differently to different pharmaceutical and lifestyle prescriptions – weight loss being a great example.

But does this mean we need a separate program for all three million overweight or obese adult Australians? And if not, how do we individualise without over-individualising?

The first law of thermodynamics states that energy is neither gained nor lost, it just changes form. We’re told that this is immutable. And yet change the energy balance (food in/exercise out) of 1000 people in exactly the same way and you’ll get a variation in weight loss from nothing, to more than the loss predicted through any calorific formula. The question is why?

The simple answer is that the first law is based on a physics formula, which is linear, eg: weight = energy in – energy out. This only works roughly, in a biological system. Feedback in a living organism, such as through changes in metabolic rate, hunger levels, and a range of other factors, make generic lifestyle prescriptions such as diet and exercise, just that – generic, with huge variations around the mean.

The implications of this are profound. A calorie is no longer a calorie. As the actual value of heat energy can be influenced differently by feedback in individuals, any attempt to prescribe or measure weight gain or loss by counting calories, is bound to be flawed.

Using a systems theory model can complicate the issue, but may be totally necessary. In the UK, the Foresight Commission, a body set up to examine the future, published a diagram of known drivers of obesity

[1] (see main image for a simplified version), which has come to be used to draw a laugh by obesity lecturers around the world.

Prescribing a set diet and exercise program alone for helping a patient loose weight may work brilliantly for some, for whom these are the immediate divers, but it may not work at all for others.

What’s the alternative? Ultimately, a computer program including genetic analysis might reduce the variability in response. But this is some way off. So what to do in the meantime?

American obesity researcher and clinician Dr Robert Kushner had a crack at this by looking at different personality types based on types of eaters, exercisers and stress managers. In his book “Dr Kushner’s Personality Type Diet” [2] (which would normally be discarded as a ‘fad’ book on the basis of its title), Kushner has developed a screening system to categorise people into 6 different types of eaters, exercisers and stress responders.

Kushner’s eating personality types are classified in such non-scientific categories as ‘unguided grazer’, nighttime nibbler’, ‘convenient consumer’, ‘fruitless feaster’, ‘mindless muncher’ etc. Despite the appeal to a public audience, each does have some scientific basis, which is added to by Kushner’s respectability as a world class obesity researcher.

Breaking the weight loss responder into different groups like this, according to Kushner, can help increase the prospects of success on a weight loss program. This is not rocket science – yet! But individual targeting in prescription, just as in marketing of consumer products, points to the way of the future. A good clinician might do this intuitively, but the increasing complexities of the modern world make it more and more difficult to do so

Kushner’s approach is a possible way of narrowing down the individual differences in weight loss response. But given that there are a number of other drivers that can influence lifestyle (including sleep, the environment, relationships, etc) don’t expect any major breakthroughs in the clinical response to weight loss.

1. Vandenbroeck IP, Goossens J, Clemens M. Tackling obesities: future choices—building the obesity system map [internet]. Government Office for Science, UK Government’s Foresight Programme; 2007. Available from:
2. Kushner RF and Kushner N. Dr Kushner’s Personality Type Diet. Folio Graphics, Bloomington IL, 2008.

This column first appeared in Medical Observer.