When it comes to weight (specifically fat) loss, I’m not into counting or consciously restricting them. I’ll come onto why in a moment. But before I do, I want to share the results of a recent study in which women ate in one or four ways :
1. where individuals ate a diet which restricted calories to 1200 per day (individuals were given pre-prepared food to eat).
2. where individuals ate a diet which restricted calories to 1200 per day in which the individuals were also required to keep their own tally of calorie intake (in other words, they both restricted and monitored calorie intake)
3. where individuals were required to monitor their calorie intake, but were not required to restrict calories
4. where individuals were allowed to eat normally.
The study lasted 3 weeks. The results, briefly, of this study were that women who restricted calories (groups 1 and 2) saw a significant rise in levels of the stress hormone cortisol. Individuals in group 3 (monitoring calories only) did not see a rise in cortisol levels, but their ‘perceived stress’ went up. In short, cutting back on calories or just tracking them is stressful.
The raised cortisol levels seen in those restricting calories may have special significance, as this hormone predisposes to weight gain, particularly around the middle. Seeing as most individuals restricting calories are doing it to lose weight, this biochemical side-effect of caloric restriction might be viewed as quite counter-productive.
It may also help explain why so, so many people who restrict calories to lose weight find this approach so ineffective in the long term. But there are other fundamental problems associated with caloric restriction that mean I am no fan of it. These include:
1. a reduction in the metabolic rate , and this is something that can take a long time to recover too 
2. a tendency for individuals to gravitate to lower calorie foods that can be quite unhealthy (e.g. artificially sweetened foods and drinks)
3. a tendency to move away from fat and towards carbohydrate – the chief driver of insulin – the hormone that drives fat deposition in the body
4. hunger – which can make this approach simply unsustainable
5. when individuals restrict calories, they tend to spontaneously move less too [2,3]
Put all of these things together and it’s not difficult to understand why caloric restriction is so often such a dismal failure for those looking for healthy, sustainable weight management. So unkeen am I about caloric restriction, that I’ve devoted a whole chapter of my new book (Waist Disposal – the Ultimate Fat Loss Manual for Men) to its perils (Chapter 2: The Calorie Trap). More importantly, perhaps, the book provides lots of information about how to escape this trap. For more information about the book, see my last post here.
1. Tomiyama AJ, et al. Low calorie dieting increases cortisol. Psychosomatic medicine 5 April 2010 [epub ahead of print]
2. Redman LM, et al, Metabolic and behavioral compensations in response to caloric restriction: implications for the maintenance of weight loss. PLoS One 2009;4(2):e4377
3. Weyer C, et al. Energy metabolism after two years of energy restriction: the biosphere 2 experiment. Am Clin Nutr 2000;72(4):946-53