Fitness and weight loss can be incredibly complex. To make things easier, the fitness industry has long relied on simple slogans to communicate basic principles. Three of the most well-known are “Eat Less, Move More,” “Calories In, Calories Out,“ and “If It Fits Your Macros“ (IIFYM).
Over time, however, these sayings have been criticized for being too simplistic, lacking context, or simply being wrong. In reality, most of the criticism comes from expecting them to answer questions they were never intended to answer. This article looks at what these sayings were originally meant to communicate, how they’ve been misinterpreted online, and why simple advice can still be good advice.
Key Points You Need To Know!
“Eat Less, Move More“ is very basic information on how to lose weight.
“Calories In, Calories Out“ simply explains the basic mechanisms of losing weight and energy expenditure.
“If It Fits Your Macros“ was meant to suggest your diet does not need to be 100% clean all the time.
All of these basic pieces of advice have been twisted by the internet and overcomplicated.
However, they’re all still true and offer the foundations of weight loss.
“Eat Less, Move More”
“Eat Less, Move More“ evolved throughout history, and while the exact time it was coined is unknown, we know it was a mainstream saying by the late 90s. Its purpose was simple: to explain how fat loss is based on the law of thermodynamics:
Eating Less would result in fewer calories consumed.
Move More encourages exercise and increased physical activity to burn more calories.
Less Calories Consumed + More Calories Burned = Weight Loss.
It’s a pretty simple concept that was at once treated as a matter of fact. While it’s not as precise as once believed, it still describes the primary mechanisms of fat loss (Christoffersen et al., 2022).
What The Internet Said It Meant
Recently, there has been pushback against “Eat Less, Move More,” and it is terribly easy to find articles blatantly saying it doesn’t work anymore.
Their claim comes down to: “It’s more complicated than moving more and eating less”. They’ll then follow with examples:
Food’s effect on hormones
The satiety of different foods
Various genetic issues
In short, they claim that more advice is needed because it’s too simple for modern life.
What The Internet Gets Wrong
“Eat less, move more“ will always be the foundation of weight loss. While modern living has created different obstacles, it hasn’t changed our physiology.
It’s why critics rarely cite evidence showing people gaining body fat while maintaining a true caloric deficit.
The only time the balance does seem to get skewed is when a person loses weight while in a caloric surplus (Reilly, 2026).
However, this is usually seen when a person eats a very high-protein diet. Protein has significantly higher TEF, so you’re still burning more calories; it’s just happening internally.
This same concept is applied to all the criticism:
Slow metabolism = Fewer calories burned
Certain foods cause less satiety = Eating more calories
Certain hormones = Less calories burned
All their criticisms actually acknowledge the importance of energy expenditure. Why would a slow metabolism even matter if weight loss isn’t determined by calories? Because it does.
There are numerous reviews and meta-analyses that equally show diet + exercise produces the best results for fat loss and improved body composition (Clark, 2015).
“Calories In, Calories Out”
Similar to “Eat Less, Move More”, “Calories In, Calories Out“ became a simple slogan to explain how weight loss occurs. It explains the basic law of thermodynamics but specifically focuses on calories instead of actions.
Originally, it was understood to explain the basics of weight loss and bring attention to calories. And this is not a new phenomenon; the first weight loss book focused on calories was published in 1918 by Lulu Hunt Peters, Diet and Health, With Key To The Calories.
What The Internet Said It Meant
Over time, the internet built a very rigid model of CICO and suggested it made claims that reached far beyond its original intent. They then criticized that caricature.
The main complaint about “Calories In, Calories Out“ is that “Not all calories are equal!“ Critics point to different foods and physiology that cause different reactions in the body:
Sugar spikes glucose
Unprocessed foods aren’t satiating
Certain foods have more nutrition
It’s very similar to the criticisms of “Eat Less, Move More“ and essentially overcomplicates a very simple concept.
What The Internet Gets Wrong
“Calories In, Calories Out“ is still good advice because it still works.
CICO was never meant to be the only nutritional guideline you ever follow. Nor did it ever suggest that food quality, hormones, appetite, and nutrient composition don’t matter.
But why would it? It’s only speaking about calories!
That’s like saying “change your oil every 3,000-5,000 miles“ is bad advice because you also need to change the filter, check the tire pressure, and different cars may require different maintenance schedules. There are also different types of oils: 10W-30, 5W-30, and 15W-40.
All true, but none negate the fact that most people should get their oil changed every 3,000-5,000 miles.
Further, many of the criticisms are actually talking about the effect of other nutrients. Your food contains varying levels of protein, carbohydrate, fat, fiber, caffeine, vitamins, minerals…there are thousands of bioactive compounds that can trigger physiological and metabolic processes.
Calories don’t. They simply quantify the amount of energy those foods contain and are innocent bystanders in this whole thing.
They’re criticizing calories for the perceived negative effects of other nutrients. The problem is, you can do this with any nutrient.
“Stop telling people to get their Vitamin C! It’s not healthy because orange juice can spike your insulin”
“Stop telling people to eat more protein! Deep-fried corn dogs have a ton of trans fats!
“Carb loading doesn’t work because Snickers has too much sugar.”
Obviously, those are silly, yet they’re essentially doing the same thing. The quality of your diet food doesn’t affect the physiological functions of calories or nutrients.
“If It Fits Your Macros”
“If It Fits Your Macros“, or IIFYM, is a basic form of flexible dieting in which you build a diet to hit your macros rather than only focusing on calories.
Your “macros“ are your three primary nutrients:
Protein
Fat
Carbs
By focusing on these, you ensure your diet delivers the right nutrients. And since it’s your macronutrients that contain your calories, that’s taken care of too.
It was an answer to the rigid diets at the time and suggested that a diet does not need to be perfect with 100% clean foods.
While not as famous today, it was all the rage in the fitness and bodybuilding scene during the 2010s. More importantly, we still see remnants of ideas that surrounded it today.
What The Internet Said It Meant
When it originated, IIFYM helped people understand that a cookie does not erase a calorie deficit. It suggested that food variety can improve adherence and that diet quality is not the same thing as perfection.
In other words, IIFYM shifted the focus to your diet’s overall composition rather than a strict list of foods. However, it was still taught alongside the idea of concentrating on whole foods and quality.
Like the internet does, forums developed with people asking:
Can I eat a cookie?
Can I eat pizza?
Can I drink soda?
Reluctantly, coaches would answer; ‘If it fits your macros“. This led trainees to start taking the phrase literally. People used it as permission to build a diet of junk and highly processed foods, provided they hit a protein target and stayed within calories.
What The Internet Gets Wrong
IFFYM might be the best example of how good advice was manipulated to mean something it doesn’t. It’s also unique as there are two camps of criticism.
Camp 1: Used it to eat whatever they want
Camp 2: Framed IIFYM off of Camp 1 and criticized it for not addressing the quality of food.
Both accounts are twisting the original intention of IIFYM. Again, the phrase “If It Fits Your Macros“ came from the frustration of experts having to repeat the same information over and over.
But their main point wasn’t that “junk food is optimal”. Rather, it was that no single food determines the success or failure of a diet. It was one of the first big movements that got away from strict calorie counting and eating 100% clean and pushed “flexible dieting”.
That’s an important distinction, and it sheds light on its true intent, one that most people would largely agree with.
It also explains why it doesn’t address other micronutrients and things like fiber. IIFYM is similar to Intermittent Fasting in that it doesn’t tell you what to eat or address the totality of your diet.
The Truth About Weight Loss
While this article looked at criticisms of these “rules“, it would be unfair not to acknowledge that some people do try to simplify it to the extreme. There is plenty of truth to the claim, “it’s more complicated than that”.
But this is the reality of training, nutrition, and fat loss. It is complex, and there are various factors that need to be addressed. However, this nuance occurs on the individual level. It’s simply impossible to give specific guidelines that satisfy everyone’s exact protocol, as that doesn’t exist.
And if you tried to address every bit of nuance found in weight loss, you would need 100 pages. Or, you could look at the 4 or 5 words for what they are
Reference List
Christoffersen BØ, Sanchez-Delgado G, John LM, Ryan DH, Raun K, Ravussin E. Beyond appetite regulation: Targeting energy expenditure, fat oxidation, and lean mass preservation for sustainable weight loss. Obesity (Silver Spring). 2022; 30: 841–857. doi:10.1002/oby.23374
Clark J. E. (2015). Diet, exercise or diet with exercise: comparing the effectiveness of treatment options for weight-loss and changes in fitness for adults (18-65 years old) who are overfat, or obese; systematic review and meta-analysis. Journal of diabetes and metabolic disorders, 14, 31. https://doi.org/10.1186/s40200-015-0154-1
Drenowatz C. (2015). Reciprocal Compensation to Changes in Dietary Intake and Energy Expenditure within the Concept of Energy Balance. Advances in nutrition (Bethesda, Md.), 6(5), 592–599. https://doi.org/10.3945/an.115.008615
O’Gorman, K. (1998, August 24). Eat less, move more: The secret of successful weight loss is to find one’s own path to the obvious. The Washington Post. https://www.washingtonpost.com/archive/lifestyle/wellness/1998/08/25/eat-less-move-more/cac571c1-8624-47a0-ac38-b05f97472ec4/ [1]
Reilly, R. R. (2026). Tipping the Scales of Body Recomposition With an Energy Surplus, High Protein Intake, and Resistance Training: A Narrative ReviewStrength & Conditioning Journal https://doi.org/10.1519/SSC.0000000000000964
Wu, T., Gao, X., Chen, M., & van Dam, R. M. (2009). Long-term effectiveness of diet-plus-exercise interventions vs. diet-only interventions for weight loss: a meta-analysis. Obesity reviews: an official journal of the International Association for the Study of Obesity, 10(3), 313–323. https://doi.org/10.1111/j.1467-789X.2008.00547.x
