There’s an endless stream of fat loss bullshit on the internet. Avoid certain foods, take obscure supplements, douse your body in a tub of ice while drinking a kale smoothie, manipulate your hormones, etc. I know, it’s unending.
But despite all the claims, fat loss will always come down to your energy balance. Here are 5 reasons why calories do count.
1. As food intake increases, so does body weight
In 2009, researchers took calorie data from 1970 to 2000 and related calorie intake to body weight to see how increased energy intake and reduced physical activity were contributing to the US obesity epidemic. 1
They found the increase in estimated caloric intake was sufficient to explain why people in the US were getting fatter.
But it’s not just the US.
A 2015 study investigated the associations between changes in the national food energy supply and the average body weight in 56 countries and found that as food intake increased, so too did body weight. 2
The researchers also noted that due to this and the decrease in physical activity, the same pattern is expected to occur in the future in low- and middle-income countries.
2. All diets work as long as a calorie deficit is present
Every popular diet claims to be the solution to your fat loss woes. Yet, when total calorie intake is controlled, none of these diets are superior to the other.
One study analysed 14 popular diets varying in macronutrient composition (low carb, low fat, and moderate macronutrient). The results showed all diets led to weight loss, with no real difference between them. 3
While low-carb and low-fat diets resulted in more weight loss compared to moderate macronutrient diets, the practical difference in weight loss at six months was only ~1.5 kg (~3 lbs), or less than half a pound per month.
3. And yes, this also includes fasting diets
Kim et al. (2022) published a meta-analysis comparing fasting diets to good ‘ol caloric restriction using evidence from randomised controlled trials published between 2011 and 2021 and didn’t find a difference in weight loss between groups when comparing the type of fasting (5:2, alternate-day fasting, time-restricted eating) or duration (8-12 weeks, 16-24 weeks, and 52 weeks). 4
4. It’s not insulin, either
Insulin is probably the most vilified hormone in the fitness space. But blaming insulin for fat gain is like your boss firing you for doing your job—it doesn’t make any sense.
Yes, it’s true that insulin is a ‘storage’ hormone. It’s also true that when insulin is released, it puts a brake on fat burning. But here’s the thing: your body is constantly storing and burning fat throughout the day.
For example, let’s say you wake up and skip breakfast – your body will use stored energy for fuel (i.e. it’s burning fat). Later, you eat lunch. Now the body stops burning stored energy and starts using the calories you just provided (i.e. fat burning is paused).
But short-term fat storage or fat burning doesn’t mean jack shit for whether you lose or gain fat; it’s the net energy balance over days and weeks that will dictate how much fat you store or burn.
If you constantly eat more calories than you burn, your body will store those excess calories as body fat. However, this isn’t because of insulin––insulin is doing its job of taking nutrients from your bloodstream and moving them into your cells.
What’s actually causing fat gain is too many calories coming into the body. Conversely, when you’re in a calorie deficit, insulin won’t stop you losing body fat because you’re in a net energy deficit, where the number of calories you’re burning outpaces the number of calories you’re consuming.
So, it’s no surprise that every good study comparing a low-carb diet to a low-fat diet has failed to find a difference in fat loss.
Take this 2018 randomised controlled trial that assigned 609 participants to either a healthy low-fat diet or a healthy low-carb diet for 12 months. Both groups lost an equivalent amount of weight by the end of the study. 5
Importantly, genetics and baseline insulin secretion had no impact on weight loss.
More recently, a Cochrane review compared the effects of low-carb diets versus a ‘balanced’ carb diet on weight loss. 6
In case you didn’t know, Cochrane reviews are considered the highest standard in evidence-based healthcare. Translation: they don’t fuck around.
Their conclusion? 👇🏼
Low-carbohydrate weight-reducing diets probably result in little to no difference in weight loss over the short term (trials lasting 3 to 8.5 months) and long term (trials lasting one to two years) compared to balanced-carbohydrate weight-reducing diets, in people with and without type 2 diabetes.
In the short term, the average difference in weight loss was about 1 kg and in the long term, the average difference was less than 1 kg.
Do you want to know the best part about the whole carb-insulin thing?
Gary Taubes––probably one of the biggest names in the low-carb space––funded a study to disprove calories-in/calories-out (or what’s more formally known as the ‘energy-balance model’), and that study disproved his own theory (I wrote about this here). But do you think Taubes changed his mind? Fuck no. In 2020, four years after that study, he published another book titled, “The Case for Keto: The Truth About Low-Carb, High-Fat Eating.”
At this point, it’s just sad. Anyway, let’s move on to the next point.
5. Tracking calories helps people lose more weight
If fat loss were down to manipulating hormones or eliminating toxins or whatever, then people wouldn’t lose weight when they control their calorie intake. Yet, that’s exactly what happens.
In one review, all 15 studies that focused on dietary self-monitoring found significant associations between self-monitoring and weight loss. 7
Further, overweight or obese individuals who consistently monitor their diet (and body weight) lose more weight than those who don’t. 8
In fact, recording how much someone eats is positively associated with the amount of weight lost and/or maintained. 9
In conclusion
People tend to gain weight as food intake increases—especially with easy access to cheaper, calorically dense foods. All diets work because, in one way or another, they make you eat less. When people are mindful of how much they’re eating, they lose weight.
The one common thread? Calorie intake.
The sooner you accept that weight loss or gain is always dictated by how much you eat, the sooner you can break free from the shackles of the diet industry.
Yes, you should do your best to eat as healthfully as possible. But even the healthiest diet in the world won’t stop you from gaining fat if you consistently eat more than you need.
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