The conventional view of energy in food is that it is measured by the bomb calorimeter, which many of us used in our physics classes in school. A known amount of material is placed in the calorimeter and incinerated. The rise in temperature is then used to calculate the energy/calorie content. Using the same principle humans can be placed inside a much more sophisticated and bigger calorimeter so that the calories expended can be measured. If these are greater than those consumed this means some of the body’s reserves have been used and therefore the individual exhibits weight loss. Similarly if more calories are consumed than are the total lost then there will be weight gain. As a consequence it has led to the assumption that weight loss can be achieved by reducing the total number of calories consumed. This has been the accepted mantra by health professionals, those who wish to lose weight and especially the weight loss industry.

The reality is that it does not work! (1). In a recent article in the Journal of the American Medical Association (2, 3) David Ludwig and Mark Friedman pose the questions:

“But what if we’ve confused cause and effect? What if it’s not overeating that causes us to get fat, but the process of getting fatter that causes us to overeat?”

They put forward the view that that there are certain factors, which stimulate the fat cells in the body to take up and store excessive amounts of constituents which are rich in calories and consequently are not available to meet the normal requirements for maintenance. In order to survive, the brain makes the person feel hungry and so more food is consumed. So while the immediate problem is solved in the short term, the long term result is weight gain and ultimately obesity. Essentially the reason the usual approach to slimming fails is that it is accompanied by persistent hunger and the only ones who succeed are those who effectively starve themselves.

The article emphasises that there is no doubt that the hormone insulin is the dominant factor which influences the storage of calories in fat cells. When excess insulin is used to treat T2D it causes weight gain whereas insulin deficiency causes weight loss. From a dietary perspective it is the consumption of sugar and refined carbohydrates which cause the production of insulin by the pancreas in order to control the build-up of glucose in the blood. So the more of these foods that are consumed the more insulin will be available. Therefore it is quite consistent that the increase in the consumption of sugar and refined carbohydrates in the USA, the UK and many other countries has been accompanied by an increase in the incidence of obesity.

In an earlier study David Ludwig and colleagues compared diets which contained the same amount of calories but very different proportions of carbohydrates and fats (4). The subjects were middle-aged men and women who were overweight or obese. They found that those on the diet containing 60% fat and 10% carbohydrates had a total energy expenditure of 3137 Kcalories /day whereas those on the low fat diet with 20% fat and 20% carbohydrates had only 2812 Kcalories/day….a reduction of over 300/day. This is a huge difference but the most important conclusion to emerge is that this confirms the fact that not all calories are equal! This should come as no surprise to anyone who recognises that the ways in which fat, protein and carbohydrate are metabolised and utilised in the body are totally different. Nevertheless the significance of the impact on the energy expenditure is absolutely crucial because it demonstrates the futility of formulating diets on the basis of calorie content irrespective of the constituents. This insight also helps to understand why the odds are stacked against the conventional calorie control approach to lose weight since a low fat diet seems to be utilised very efficiently with energy loss kept to a minimum. The study also monitored some of the other indicators of health and in general the more favourable results were obtained with the high fat diet. In particular, the levels of triglycerides, a heart disease risk factor was 107 mg/dl in those on the low fat diet but only 66 mg/dl in those on the high fat one. In fact work with rats has suggested that even on a low calorie diet which is high in refined carbohydrates, there is a tendency towards obesity as shown by fat deposition (5).

There really is nothing new about the findings. Over 50 years ago, Kekwick and Pawan conducted a series of experiments with iso-caloric diets (all with the same calorie content) and concluded that the:

“..rate of weight loss varied so markedly with the composition of the diet on a constant calorie intake, it is suggested that obese patients must alter their metabolism in response to the contents of the diet. The rate of insensible loss of water has been shown to rise with a high-fat and high-protein diets and to fall with high-carbohydrate diets” (6).

There have been a number of other investigations which all reach similar conclusions but have not been accepted by mainstream nutritionists on the grounds that the results do not comply with the First Law of Thermodynamics. This states that the  total energy of an isolated system is constant; energy can be transformed from one form to another, but cannot be created or destroyed. However this logic is totally fallacious because the First Law relates to an isolated system and therefore we need to have information on all the energy inputs and outputs. As the study by Ludwig and Friedman showed there is marked variation in the energy loss with the diets of different composition, the fact that weight loss varies is entirely consistent with the First Law. Those who claim that the variation in weight loss is in conflict with the First Law are obviously making the false assumption that the energy retained in the body will be precisely the same for every diet irrespective of the composition. Clearly this is impossible and therefore wrong because the biochemical steps involved in the breakdown and utilisation of fat, protein and carbohydrate are all different. There is ample evidence available to confirm this. For anyone interested in a more detailed consideration of this issue plus a discussion of the role of the Second Law of Thermodynamics, consult this reference (7).


The focus on calorie control as a means of weight loss is based on a fundamentally flawed concept. It does not work and there are millions of people who can confirm this from their own personal experience. The message is quite clear. It is not the amount of food which determines your weight or your ability to lose it but the quality in terms of the relative proportions of fat and carbohydrate. If you wish to lose weight and improve your health then it is abundantly obvious that the answer is to reduce the carbohydrates and increase the fat.


  1. https://vernerwheelock.com/?p=218
  2. http://jama.jamanetwork.com/article.aspx?articleid=1871695
  3. http://www.nytimes.com/2014/05/18/opinion/sunday/always-hungry-heres-why.html?_r=0
  4. http://jama.jamanetwork.com/article.aspx?articleid=1199154
  5. http://www.ncbi.nlm.nih.gov/pubmed/15337404
  6. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(56)91691-9/fulltext
  7. http://www.nutritionj.com/content/3/1/9


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