Several crucial changes in energy intake and expenditure patterns have occurred in the United States in the last 40-50 years. According to an article published in the Journal of Economics and Human Biology, between 1971 and 2000, the total individual caloric intake increased, while the proportion of intake from dietary fat decreased and the proportion from dietary carbohydrate increased. Within the same time frame, caloric intake from fat remained largely unchanged, while caloric intake from carbohydrates (and in total) increased. Additionally, the use of caloric sweeteners increased considerably in a similar time frame (1962-2000).
Despite the fact that time-use surveys indicate that leisure-time physical activity remained largely unchanged, the average energy expenditure related to occupations decreased by more than 100 calories between 1960 and mid-2000s. This reduction in energy expenditure occurred in conjunction with the doubling of obesity prevalence since the early 1960s.
'A calorie is a calorie' is a phrase that is trivially true in many respects but incites confusion all at the same time. The phrase is questionable on the basis that it leads us to believe that, where the effect on body weight is concerned, fat must be bad because fat is calorie-dense per unit of weight, and that carbohydrate and protein are good because they contain relatively few calories. In addition, the phrase also assumes that in terms of weight lost or gained, there is no difference between diets that contain the same number of calories say from potatoes, green vegetables, and fish, or from soda, burgers and french fries.
In their clear-cut commentary on the issue of calorie-focused thinking when it comes to obesity and related diseases, Sean Lucan of the Albert Einstein College of Medicine, New York, and James DiNicolantonio of the Mid America Heart Institute at Saint Luke’s Hospital, Kansas City argue that this premise, upon which nutritional teaching has been based for more than a century, is wrong. In fact, the classic case studies of individuals who experience an increase in body weight or those who try to maintain a decreased body weight - or body fat - consistently contradict the 'a calorie is a calorie' mentality.
Physiological Effects of Calories
The physiological effects of different calorie sources are an important consideration for weight management nutrition. For example, a calorie's worth of fish (mostly protein) and a calorie's worth of olive oil (pure fat) exhibit very different biological effects than a calorie's worth of white rice (refined carbohydrate) or a calorie's worth of whisky (mostly alcohol) - particularly in relation to body weight and body fatness.
Even though much of our early knowledge on the topic was acquired from animal studies, later studies that used human subjects have shown that energy-providing fats, proteins, carbohydrates and alcohol all have varying effects on a wide range of physiological pathways and hormones relating to satiety, food consumption, body fat composition, and the maintenance of body weight.
In fact, different nutrients of equal caloric content have various effects on body weight. In order to grasp this concept, we must first understand that certain nutrients may be metabolized more efficiently than others since the consumption of a given nutrient may result in greater net energy storage (the storage of body fat, for example) and less waste. Simply put, certain foods can be considered more 'nutritious' than others in terms of their energy conversion.
The 'Eat Less, Move More' Mantra
The trouble with attempting to 'eat less' and 'move more' to achieve (and maintain) a caloric deficit or negative energy balance is that it is practically and biologically implausible.
From a practical perspective, even the savviest individuals cannot make estimations of their actual calorie absorption or their true calorie expenditure with enough accuracy to produce a useful and continuous calorie balance sheet. This type of practice is challenging at the very least due to misleading food labels and the fact that calorie intake does not equal calorie absorption. In addition, the monitoring of energy expenditure requires the consideration of the constant fluctuation of digestive and metabolic processes to produce meaningful results.
Biologically, calorie intake and calorie expenditure are interconnected and, unless considerable uncoupling occurs, decreasing calorie intake will inevitably result in a compensatory push to decrease calories expended, and vice versa. Therefore, individuals who reduce their calorie intake become tired as a result of an expenditure compensation, and hungry due to intake compensation.
Calorie-Focused Food Labeling
This is a very controversial topic since government regulatory organizations prioritize the display of calories on the compulsory labels of processed food products and implicitly suggest that customers calculate their 'daily values' of calorie intake with reference to daily turnover averages. The importance of macronutrients on these products' labels is determined by their serving sizes-to-calorie 'daily values', which is ineffective and almost totally impractical.
However, this tactic is clearly advantageous to the manufacturers since, according to a study by the Hudson Institute, packaged goods companies promoting low-calorie products that are supposedly 'better for you' achieve superior sales growth, larger operating profits, and operating profit growth. All the while, research indicates that food marketing to children and adults in the United States continues to promote products that are high in sugar.
What is potentially even more concerning is that several nutrition scientists still carry this 'a calorie is a calorie' approach to their academic work and practical endeavors. As a result, for well over 50 years, government, industry, and science have come together in support of a general understanding of food, nutrition, health and disease which is wholly erroneous.
A Calorie in the Meter is not a Calorie in the Body
Acknowledging that the calories in/calories out approach to weight management are not a logical path to follow will not automatically reverse the rates of obesity and disease alone; we also need to concentrate on the dietary components that are most rapidly absorbed in the human body.
In line with their rating on the glycaemic index, carbohydrates differ in their digestibility and timing of ingestion, and a growing body of research indicates that some sources of carbohydrates - notably fructose - may play a strong role in increased obesity. In a 2018 study that investigated the effects of a low carbohydrate diet on energy expenditure during weight loss maintenance, researchers found that total energy expenditure was significantly greater in subjects who were assigned to a low carbohydrate diet compared with a high carbohydrate diet which included similar amounts of protein.
Another study investigating the link between sugar-sweetened beverages and the genetic risk of obesity further supports the hypothesis that measured calorie content does not have a strong relationship with the development of obesity. The authors of the study found that, even after individuals performed self-reported total energy intake and expenditure measures, the intake of sugar-sweetened beverages strengthened the association between the risk of obesity and the genetic susceptibility to obesity.
These findings are not only significant in academia; obesity and diabetes (the disease most closely causally related to obesity) are now considered epidemics which, according to a speech by the Director General of the World Health Organization (WHO), no country has been successful in controlling. Lucan and DiNicolantonio explain that their lack of control is due to the fact that the standardized advice to 'control calories' is misguided, and diverts the attention of the individual from lifestyle and dietary choices that are actually more likely to prevent an increase in weight and promote the maintenance of a healthy weight.
In addition to focusing on rapidly absorbable carbohydrates, an element that must not be overlooked is how foods are prepared, combined and consumed. Foods that are minimally processed and rank as being 'bad' on the glycaemic index based on their analysis in isolation are not generally eaten by themselves.
For example, white rice is a rapidly absorbable carbohydrate when consumed in isolation. However, white rice is a staple in many countries within Asia and Latin America where it is combined with vegetables or legumes and prepared as a freshly cooked meal which then alters its metabolic effect immensely. The Brazilian Government took these very important factors into consideration when publishing the Dietary Guidelines for the Brazilian Population in 2015.
There is a growing body of evidence that links the consumption of refined carbohydrates with increases in body weight. In addition, the research suggests that, even when individuals control their total calorie consumption, an increase in the consumption of carbohydrates is associated with both short- and long-term increases in body weight. An increase in fat consumption, if anything, is associated with a reduction in body weight which possibly explains the recent popularity of the keto diet and paleo diet.
Focusing on the number of calories in food ignores the wide-ranging metabolic effects of the foods themselves. Highly processed foods that consist mostly of rapidly absorbed sugars and starches are of a particular concern as carbohydrates such as these may lead to neurohormonal changes that might cause subsequent overeating and physical inactivity which are commonly viewed as causative for obesity.
If the customer's lack of knowledge in the effects of combining various nutrients for a given caloric content, and when considering that weight gain is a gradual process which offers no immediate feedback, a calorie-counting customer may unintentionally affect their weight accumulation by shifting consumption across nutrients while only monitoring total calories. Individuals who consume these unhealthy foods suffer in more ways than one; they become obese by eating them and receive unpleasant criticism for their large appetites and seeming laziness that result.