Calorie Restriction – Unpacking The Research

This blog has been written by James St Pierre, Owner and Personal Trainer here at Unique Results.

Mike Sweeney (the Registered Dietitian who works closely with us) recently shared with me this letter he wrote in response to a client’s questions around calories and the role they play in weight loss and weight maintenance. We know that nutrition is an emotive and confusing subject for many people which is why I liked this response so much and asked to share it with you. Please have a read and if you have any questions around it please talk to one of the team on your next visit.

It seems like you have some fairly strong views on nutrition which is great because as we all know nutrition is super important. It’s true that TBT is, and has been for some time, committed to helping women live healthier and stronger lives. We take our role seriously which is why we don’t just read popular books and decide whats right we do actually work with qualified professionals. On our “team” is an ex-NHS Dietitian who works in the background and informs and trains us on everything we do when it comes to nutrition.

It sounds like you believe Jason Fung, MD – author of a book called “The Obesity Code” – to be a leading expert in the field of obesity and possibly nutrition. What makes you think that his view is the only valid view on this topic? It’s worth noting that Mr Fung is a nephrologist – a literal expert in the kidneys and any diseases related to the kidneys. To my knowledge they aren’t specifically trained in nutrition science which is why Renal Dietitians do exist – to handle the nutritional side of any kidney diseases.

But that’s besides the point…

His book overall makes some good valid points by pointing out that obesity is an holistic problem. Simply meaning that there are multiple factors like poverty, environmental influences, genetics, hormones etc.

It’s interesting you keep using the word “calorie theory” because Jason Fung’s own recommendations of intermittent fasting + eating only “clean” foods leads to what exactly?

A caloric deficit.

Put simply if you followed his instructions you’d be eating LESS. There’s nothing wrong with his recommendations of course but that doesn’t mean that calories don’t matter and that doesn’t mean insulin causes obesity.

For example, bodybuilders are the leanest athletes on the planet. Yet they eat a high carb diet. Interesting, right?

Let’s unpack some science here

Consider this randomised controlled trial done in 2012 where researchers wanted to figure out if different diets affected weight gain differently.

First thing to note is it’s a metabolic ward study. This means the people were literally locked in a hospital unit so their food intake could be precisely controlled thus minimising any interference from outside factors. This is the most controlled type of scientific study possible.

The people in this trial were provided with a range of different diets: low protein / high protein / low fat / high fat / low carb / high carb etc.

Here’s what they concluded, and I quote:

“Among persons living in a controlled setting, calories alone count for the increase in fat; protein affected energy expenditure and storage of lean body mass, but not body fat storage.”

You can read the full study here:

Take away point

Calories alone account for increase in bodyfat

Now granted there are multiple reasons why someone may increase their caloric intake, knowingly or otherwise, which is why at TBT we take a more holistic and dare I say it “balanced” approach.

But wait theres more

In 1996 the University Hospital of Geneva carried out a 12 week study to see if different diets affected weight loss differently. Some people followed a low carbohydrate (therefore low insulin) diet….whilst others followed a high carbohydrate (therefore high insulin) diet. Now if insulin leads to bodyfat storage we’d expect the high carb diet to result in less weight loss, right?

The low carb group lost 8kg.

The high carb group lost 7.1kg.

The study concluded: “Neither diet offered a significant advantage when comparing weight loss or other, metabolic parameters over a 12 w period.”

You can read the full thing here

Take away lesson: when calories are controlled the composition of the diet doesn’t really make a huge difference when weight loss is concerned.

Yet more…

Consider this 2015 metabolic ward study that compared low carb to low fat diets and looked at how much weight people lost. These researchers found the same thing: both diets led to weight loss (more specifically, body fat loss). 
Since locking people up in hospital wards for long periods of time isn’t possible these days, they used a computer simulator to predict the effects of these different diets over 6 months.

They found very little difference between the diets. The predictor of weight loss was caloric restriction.

Here’s what the researchers actually said:

“we suspect that previously observed differences in weight loss and body fat change during outpatient diet interventions (Foster et al., 2010, Gardner et al., 2007, Shai et al., 2008) were primarily due to differences in overall calorie intake rather than any metabolic advantage of a low-carbohydrate diet.  Furthermore, we can definitively reject the claim that carbohydrate restriction is required for bodyfat loss”

You can read the full thing here

Weight loss & health

Whilst we want people to lose weight and be healthy, they aren’t explicitly linked. This study from 2016 (click here) demonstrated that weight loss in and of itself leads to improvements in health, regardless of dietary approach. Which is likely why Dr Mark Haub, a nutrition professor from the Kansas State University, ate a junk food diet that was calorie controlled and not only lost weight, but got healthier by all measurable markers.

You can read more about that here:

Link 1

Link 2

Link 3

Link 4

Take away lesson

Eating for health and eating for weight loss aren’t explicitly linked.

In summary..

There’s nothing wrong with what Jason Fung is recommending: eat healthier and do some intermittent fasting. Again worth pointing out that both those things leads to a caloric deficit. And as I’ve pointed out above, the caloric deficit is ultimately the deciding factor. Now granted there are lots of things that influence this like our mood, emotions, environmental factors, poverty etc etc Which is again why at TBT we take a more holistic approach. What we’re NOT saying is “eat crap and lose weight”. We’re simply trying to make it easy for people to lose some weight and regain some confidence. And the science says they can do that whilst still enjoying the occasional pizza, pasta dish or glass of wine (yay).

From experience once people have regained their confidence and lost some weight they naturally eat higher quality foods over time and therefore overtime because of this (coupled with the weight loss) become healthier. I really hope you can see Sandra that we are doing the right thing here. We’re not saying Jason Fung is wrong. But neither is caloric balance a “theory” – its a scientific fact. Ultimately we want women (and men) to choose whatever approach to food is most sustainable and enjoyable for them – which is why we don’t push restrictive diets.

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