Calories have become synonymous with nutrition.
AAFCO and FEDIAF base their nutrient requirements on them and traditional vets rely on the lower calorie foods to reduce the obesity concerns amongst many dogs, or indeed cats.
Over the years I have come to question the concept of Calories for several reasons. I am keen to present my thoughts to you, and I hope to bring a deeper understanding of the concept of Calories, how they originated, the true biology behind the concept of them and also how we may best go about balancing a dog’s weight as a pet nutrition consultant.
Calories or percentage method?
In fresh feeding it is customary to use what is known as The Percentage Method.
The exact invention of this method is hard to determine, however it is used with supreme success as long as the guardian or consultant is aware of the differing percentages for small, medium and larger adult dogs, and the percentage by growth amounts for puppies*.
Occasionally, the amount fed in percentage matches a suggested calorific value on software formulation. Often, though, the two do not meet, since grains and vegetables contain less fat, and therefore, more than would usually be suitable are needed to meet the calorific value.
The irony being then that the grain or starch vegetables encourage a stronger insulin release, which is known to directly contribute to the laying of fat. It was this concept that initially led me to begin questioning the concept of calories, at least for dogs and cats. Currently it is customary to consider calories when producing a balanced diet or diet formulations a guardian can share with their vet. We advise at the APNC to continue including it if it is requested, and to be aware of these explanations to support any variance between the diet formulated for the health of the pet, and any possible misalignment in the presumed calorific requirements.
Are they rooted in science?
Calories were invented, or rather theorised, well before their current scientific reasoning ATP in cells (adenosine triphospahte) was discovered, almost 50 years before at least. A French engineer, Nicolas Clement-Desormes came up with the concept to support the efficient running of steam engines, with a scale of 1 calorie being the amount of energy required to heat 1kg of water by 1 degree centigrade. Titling them a Calorie using the Latin word for heat : calor.
In 1880 an agricultural chemist named Wilber O.Atwater developed the Bomb-Calorimeter which used the same formula. Food types were burnt to ash in the device with the resulting measurement of calories noted each time. Atwater discovered that Fat gave off the most heat and so fats were deemed more calorific. He presumed the stomach was thus like a furnace, despite this not being true, and thus the beginnings of the calorie as a concept were set.
The concept was given much PR, as we call it these days, and widely suggested to the masses in order to support food advisories that the government suggested to the population. One was the concept that alcohol is bad for you, whether it is or is not, the advice in the late 1800’s was to avoid it due to its high calorific value. Alcohol combusts very easily, and thus produces a very high calorific value. Another more recent example is the advice that fat is bad for us, to be avoided and replaced with foods with sugars or grains instead.
Neither concept has proved to be true. Alcohol certainly does combust and produce high calorific values, yet many alcoholics notoriously become thinner and thinner in the end, only piling on weight if the alcohol also contains a volume of grain or if the damaged liver affects the body in such a way. Studies* have since shown that rats given alcohol put on considerably less weight than rats offered none even when their calorie intakes were identical.
The study highlights a misjudgement in the Calorie concept in that not all calories are actually bio-available, alcohol produces heat, but not the type to stick around in the body.
In Perfected by Lack, Dr Patton* expertly describes where the all fat is bad advisories have failed to support health in pets; his entire reasoning also applies to humans too. The idea that fat is the enemy is now becoming understood as more complex, with good fresh-natural fats and bad heated-trans fats playing a role*, and the health implications of the advised alternative choices to fats – such as grains and sugars, being equally as negative, often worse, for the body.
Studies on nuts*, for instance, have consistently shown that whilst being high in calories, they actually promote weight loss, not gain, another anomaly in the calorie concept.
A study in 2003* also found that subjects given diets high in fat, low in carbs lost twice as much weight as subjects given a low-fat, high carb diet. Anyone who recalls the Atkins trend may recall just how far some dieters went in attempts to lose weight using this evidence.
So, we see that Calories do not have a root in either biology or indeed any real science. Rather in theorisation, presumption and government propaganda initiated in the late 1800’s.
But what about ATP?
50 years following the Calories launch into human psychology in 1929 came the discovery of the ATP process in cells. It has since become the go-to to describe and validate the concept of calories in nutrition.
What is almost never shared is that ATP is actually inhibited by certain molecules in food, enhanced by others. ATP is part of the function of the mitochondria, and the uptake and assimilation of fatty acids too.
Glucose, for instance, has been shown to have 4 calories per gram in the bomb-calorimetre, and glucose supports the mitochondria. Glucose stimulates enzymes such as AMP-Kinase (which tells the body to make more mitochondria) and HADH (Hydroxyacyl-Coenzyme A dehydrogenase) which acts to make sure carbon molecules are oxidised (burnt) for energy. It’s safe to say glucose is good for ATP.
However, take Fructose (which is not just in fruit! It’s the other half of sucrose, the sugar molecule). Fructose actually inhibits the mitochondria and ATP.
Fructose is know to inhibit three major enzymes: one is the AMP Kinase itself; another is Acyl-CoA dehydrogenase the initial step of each cycle of fatty acids to be oxidised; and the third is CPT1 carnitine acyltransferase, linked with carnitine to break down move fatty acids to the mitochondria for energy.
Despite having 4 calories per gram fructose does not produce ATP, it in fact inhibits energy production which ultimately leads to mitochondrial disfunction and systemic health problems.
Should we use ATP as a value to validate the concept of calories if it is inhibited from occurring by certain food types?
With both the stomach as a furnace presumption not being a biological truth, and the value of ATP to explain calories being debunked, the question of why Calories were so fervently pushed as scientific remains.
Hidden in Calories
We touched on the propaganda that the concept of Calories was able to perpetuate earlier in the article, but the belief in them is also allowing, by design or default, processed foods with a high sugar, low fat profile to be considered better for weight loss, or simply better for overall health. As we know this is gradually being debunked in human nutrition, and considerably questioned in pet nutrition now, too. Whilst we focus on calories we are missing the bigger picture that insulin, and insulin resistance, has a bigger and more detrimental effect on cells, the brain, mental health, physical health, and inflammation – a whole plethora of modern western dis’ease we see regularly in both pets and their guardians too.
The USCF documents library contains open documents where in decades past scientists have been asked to promote propaganda, and ‘put science behind’ dubious metabolic biology, for the benefits of a food corporation*.
A better understanding of how and why weight is gained, the different metabolic functions and what really matters for health is called for.
By all means include the Calories in your recommendation sheets to clients, but be armed with the knowledge that it’s more peace of mind for the vet, and how to explain yourself should they question your proposals.
References top-bottom
*Rats and Alcohol : https://doi.org/10.1590/S0100-879X2004001200009
*Ruined by Excess, Perfected by Lack – Dr Richard Patton, Nottingham Press
*Fats that Heal, Fats that Kill – Udo Erasmus, Alive Books
*Nuts : American Journal of Clinical Nutrition 2003 https://pubmed.ncbi.nlm.nih.gov/12936960/
*Fats & Carb Weight study – https://academic.oup.com/jcem/article/88/4/1617/2845298
*USCF documents Dr Robert Lustig – Fat Chance & Metabolical, books Hachette publishing