Counting Calories is a fool's errand because it doesn't work
Counting Calories to create a Calorie deficit in the hope of losing weight doesn't work. We have known this for as long as we've been counting Calories.
Stone Age man didn't count Calories.
The Romans didn't count Calories.
The Crusaders didn't count Calories.
The Victorians didn't even count Calories.
Nobody counted Calories until it became popular to do so around a hundred years ago following the publication in 1918 of Diet & Health: With Key to the Calories.
Written by American doctor and author, Lulu Hunt Peters, Diet & Health: With Key to the Calories was the first weight-loss book to become a bestseller, selling over two million copies.
I wouldn’t recommend the book if you are easily offended. Fat friends of the author are given pseudonyms like Mrs Sheesasite, Mrs Gobbler, and Mrs Weyaton. The book also says that fat people in tight clothing “should be interned”, given the need for food rationing during the Great War.
As for those who advocate vegetarianism on the grounds of “the animal has just as much right to life, liberty, and pursuit of happiness as we have,” Hunt Peters' retort is blunt: “Survival of the fittest”. She then borrows a line from Benjamin Franklin, saying that if fish can eat each other, she can eat them too.
Diet & Health: With Key to the Calories was also the first book to bring Calories to the public’s attention. Indeed the focus on Calories gave it an air of scientific authority. The author wanted the word to become part of everyday vocabulary, just like pounds, gallons, and yards. “Instead of saying one slice of bread, or a piece of pie, you will say 100 Calories of bread, 350 Calories of pie.”
The book used a simple rule to calculate how many Calories you require: 15-20 Calories a day per pound of weight, depending on activity levels. If you were physically inactive, 15 Calories per pound of body weight would suffice. So, if your ideal body weight was 150lb (68kg), and you led a sedentary lifestyle, then you required 2,250 Calories a day. To lose weight, you simply subtract 500-1,000 Calories per day, much like we are told today.
This all sounds old hat to our jaded ears, but at the time the book was revolutionary. Nobody had counted Calories to lose weight before. Few had even heard of Calories before.
Lulu Hunt Peters was also the first to advocate slimming classes, advising readers to “round up the overweights” and start a local weekly Watch Your Weight class, complete with scales. The similar-sounding Weight Watchers didn’t launch until 1963.
Why counting Calories doesn't work for weight loss
On the face of it, Calorie counting makes sense.
If you want to lose weight, you require a Calorie deficit, and without counting Calories, how do you know you are running a deficit?
But counting Calories to create a Calorie deficit doesn’t lead to weight loss. Not in the long run, not for most people.
What’s more, we knew it didn’t work within a year of Diet & Health: With Key to the Calories being published.
1919 saw the publication of the study, Human Vitality and Efficiency Under Prolonged Restricted Diet, by Francis Benedict. A world-famous chemist and nutritionist, Benedict was a true pioneer in the study of metabolism and energy use in humans and animals.
Unlike Lulu Hunt Peters, however, Benedict's interest in restricting Calories was not related to voluntary weight loss. Obesity was rare at the time, but there was an epidemic of a different kind plaguing much of Europe: food shortages brought on by the war. Benedict wanted to know what effect this reduction in Calories had on men and their ability to go about their daily business.
His study involved 24 healthy male students of normal weight who maintained their normal every day activities while reducing their daily Calorie intake from 3,800 Calories to 1,800 Calories. This continued until they had lost 10% of their body weight.
The results demonstrated everything we know about metabolic adaption and the body's unwillingness to give up valuable energy reserves without a fight. As Benedict noted, “when the body weight was rapidly falling, all of the factors of metabolism and all of the physiological activities were markedly depressed”. Participants lacked energy, sweated less during exercise, lost interest in sex, were more irritable, and felt the cold more than students not taking part.
It was also found that the energy used while on a treadmill was “appreciably lower when the men were on restricted diet than with normal diet”, implying greater energy efficiency. Benedict was also perhaps the first to record that both eye movement and finger movement decreased as weight was lost, a tell-tale sign that the body is putting the brakes on energy use.
Basal Metabolic Rate (BMR) fell by between 15-20% during the weight-loss phase of the study, and was “strikingly lower than the predicted values from the analysis of a large group of normal people” of equal weight, height and age. Again, classic metabolic adaption. BMR plummets to preserve energy. This was all the more remarkable because average BMR was higher than average before the experiment began due to the high level of physical activity being undertaken by the participants, many of whom were college athletes.
While acknowledging that “body weight is an extremely unsatisfactory and indeed crude index of caloric needs”, Benedict’s study made clear that standard tables showing Calories required to maintain a certain weight only applied when weight was stable, and not when it was arrived at through Calorie restriction.
When 10% of weight was lost, Benedict found that only “one-third to nearly one-half of the normal diet” was required to maintain that lower weight.
Despite requiring 3,800 Calories to maintain weight at the study’s outset, when participants now ate more than 2,100 Calories they stopped losing weight and started to put it back on.
When the weight-loss part of the study was completed, the students were allowed to eat and drink whatever they wanted. Instead of returning to eating 3,800 Calories a day, some ate more than 5,000 Calories. “The men craved food after the restricted diet,” noted Benedict, “and especially desired sweets and accessory foods of all kinds.” Accessory foods are what we call snacks. If you’ve ever ended a diet by binge-eating junk food, you’ll know what Benedict was describing.
Francis Benedict 1870-1957
The study lasted for four months in total, but it took an average of just 13 days for participants to regain weight lost. “In practically every instance the weight prior to the beginning of the experiment was reached almost immediately and was usually materially exceeded.”
The average starting weight was 67kg, and after weight loss the average weight fell to 60kg. Three months after the study ended, the average weight of the group had increased by 4kg (9lb) compared to baseline. This led Benedict to recall a small experiment conducted in the Autumn of 1905 involving five students who were subjected to a two day fast. By January, 1906, all five men had made measurable gains over their initial weight. It appeared that anything that involve weight loss, even over as short a period of two days, eventually led to weight gain beyond that lost.
Although not the purpose of his study, Benedict had shown that restricting Calories to lose weight is self-defeating.
Benedict clearly demonstrated that Calorie restriction doesn’t lead to permanent weight loss, but results in metabolic adaption followed by weight gain.
Unfortunately, Benedict’s 700 page scientific tome wasn’t the bestseller that Diet & Health: With Key to the Calories was. With the war now at an end, the impact of food shortages was no longer a hot scientific topic, let alone of wider interest.
Had obesity been anything other than a medical curiosity at the time, the results of the study would have raised eyebrows about the merits of dieting for weight loss. As it was, nobody was looking for scientific evidence to counter the dieting advice of Lulu Hunt Peters.
Unfortunately, our continued obsession with counting Calories means we’re still paying the price for not setting the record straight immediately.
REFERENCES
- "Human Vitality and Efficiency Under Prolonged Restricted Diet" by Francis Gano Benedict (Carnegie Institution of Washington 1919)
- "Diet & Health: With Key to the Calories" by Lulu Hunt Peters (The Reilly and Lee co 1918)
Article last updated: 17th January 2021
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