Beware, not all calories are created equal − where we get our calories from counts

Written by Nyomi Graef

When I was at university studying my nutrition degree in the '90s, I learnt about calories. I was taught that all calories are equal; it doesn’t matter where they come from. A calorie is a calorie. Just burn more calories than we consume, and we will lose weight. Fat contains more calories per gram than both carbohydrates and protein, so to lose weight, keep our fat intake low.
 
Fast forward more than 20 years and many leading health experts are disproving the notion that all calories are equal. Yes, calories play a role in body weight – portion sizes matter. But research shows that not all calories are equal, and where we get our calories from counts. The calories from fat, carbohydrates and protein affect our bodies differently. Consuming too much added sugar, in particular, is linked to weight gain, type 2 diabetes and many other diseases. So for better health and easier weight loss, a low intake of added sugars from food and drinks is key.
 
What do some leading health experts say about the effects of calories on health and body weight?
Endocrinologist and obesity expert Professor Robert Lustig explains his research on calories, and how calories differ in his article Do you believe a calorie is a calorie? Below is an excerpt from Dr Lustig's article:
 
“Calories from added sugar are different from other calories, and are jeopardizing health worldwide. And yes that includes honey, syrup and High Fructose Corn Syrup (HFCS). Excess added sugar leads to, diabetes, heart disease, and fatty liver disease, unrelated to its calories. Avoid processed foods and sodas; they’re loaded with added sugar.

There's an irrefutable link shown between diabetes and added sugar.

... We found that total caloric availability was unrelated to diabetes prevalence; for every extra 150 calories per day, diabetes prevalence rose by only 0.1 percent. But if those 150 calories were from added sugar, diabetes prevalence rose 11-fold, by 1.1 percent.”

Associate professor Dariush Mozaffarian, from Harvard Medical School, has a similar point of view about calories as Dr Lustig, for instance both say that not all calories are the same, and there is more to weight gain than simply consuming more calories than we use.

According to Anahad O’Connor, from the New York Times, Dr Mozaffarian “said that the long-held idea that we get fat solely because we consume more calories than we expend is based on outdated science.
 
He [Dr Mozaffarian] has studied the effects that different foods have on weight gain and said that it is true that 100 calories of fat, protein and carbohydrates are the same in a thermodynamic sense, in that they release the same amount of energy when exposed to a Bunsen burner in a lab. But in a complex organism like a human being, he said, these foods influence satiety [the feeling of fullness], metabolic rate, brain activity, blood sugar and the hormones that store fat in very different ways.”
 
Read more about Dr Mozaffarian’s work, and other health experts’ views about calories, health and weight gain, in O’Connor’s article ‘Fed Up’ Asks, Are All Calories Equal?
 
Celia Smoak Spell, Assistant Editor at Harvard Health Publishing, also summarises the concept of calories being different. She says:
 
“It is true that fat has more calories than carbohydrates, including sugar. But by that logic, a sugary beverage is better for you than a handful of nuts. That’s just not what the unbiased studies have shown. Looking only at calories ignores the metabolic effects of each calorie; the source of the calorie changes how you digest it and how you retrieve energy from it.”
 
For more details check out Spell's article There’s no sugar-coating it: All calories are not created equal. 

Dr Mark Hyman, MD, also wrote an article explaining how calories aren’t all created equal. He said:

“That well-worn notion—that as long as you burn more calories than you consume, you will lose weight—is simply dead wrong. ... In a laboratory, or “isolated system,” 1,000 calories of broccoli and 1,000 calories of soda are, in fact, the same. ... But sorry, your law of thermodynamics doesn’t apply in living, breathing, digesting systems. When you eat food, the “isolated system” part of the equation goes out the window. The food interacts with your biology, a complex adaptive system that instantly transforms every bite."

To illustrate this concept, Dr Hyman discussed how consuming the same number of calories from broccoli and soft drink have vastly different effects on the body. In summary, the calories from soft drink are unhealthy, and can harm us, but the calories from broccoli are healthy. After explaining the differences in more detail, Dr Hyman wrote that:
 
"In a study of 154 countries that looked at the correlation of calories, sugar, and diabetes, scientists found that adding 150 calories a day to the diet barely raised the risk of diabetes in the population, but if those 150 calories came from soda, the risk of diabetes went up by 700 percent.
 
Some calories are addictive, others healing, some fattening, some metabolism-boosting. That’s because food doesn’t just contain calories, it contains information. Every bite of food you eat broadcasts a set of coded instructions to your body—instructions that can create either health or disease.”
 
For more details read Dr Hyman’s article Why Calories Don’t Matter. 
 
So to lose weight and be healthy, consume a low amount of calories from added sugar, and most calories from vegetables and other healthy unprocessed and minimally processed foods, healthy fat and healthy sources of protein.
 
How much added sugar a day is recommended?
The World Health Organization (WHO) recommends that adults and children reduce their total energy a day from free sugars to less than 10 per cent of total calorie intake. “A further reduction to below 5% or roughly 25 grams (6 teaspoons) per day would provide additional health benefits.”
 
What are free sugars? The WHO says that free sugars are sugars “... added to foods and drinks by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates.
 
“We [the WHO] have solid evidence that keeping intake of free sugars to less than 10% of total energy intake reduces the risk of overweight, obesity and tooth decay,” says Dr Francesco Branca, Director of WHO’s Department of Nutrition for Health and Development. “Making policy changes to support this will be key if countries are to live up to their commitments to reduce the burden of noncommunicable diseases.”
 
The WHO guideline does not refer to the sugars in fresh fruits and vegetables, and sugars naturally present in milk, because there is no reported evidence of adverse effects of consuming these sugars.”
 
Read the WHO’s recommendations about sugar at https://www.who.int/mediacentre/news/releases/2015/sugar-guideline/en/
 
Want more information about calories?
Check out the following article, video and TEDx talk:
 
Kris Gunnars’ Healthline article 6 Reasons Why a Calorie Is Not a Calorie.
 
Dr Jason Fung discusses how not all calories are the same in the short video titled Counting calories is a ridiculous way to try and lose weight. The video is part-way through the NBC News article A diet for fast weight loss is a pipe dream. So why do we all keep buying in? Dr Fung  also explains what happens to our bodies when we reduce our calorie intake.
 
Neuroscientist Krzysztof Czaja explains calories in the TEDx talk Why diets fail; it's not what you think. Hear how rats fed different amounts of fat and sugar gained different amounts of body fat. The rats on a high-sugar diet gained more weight than the rats on the low sugar-diet, despite the rats on the high-sugar diet eating less calories.