I went to nutrition school a long time ago. Nutrition is a dynamic science, meaning it’s ever-changing. So it’s understandable that some of the things I learned back in the 90s aren’t what we know now. 

I’ve had trolls on social media tell me that I got my nutrition degree so long ago, so I can’t possibly be up to date on what’s going on now with food, diets, and how they affect our bodies.

Yeah, right. Sorry, suckers!! Like any profession, dietitians don’t do their schooling and then regurgitate the same information for decades. Most of us are completely up to date with current studies and science around nutrition.

Here’s a list of some of the most incorrect things I learned way back in nutrition school, and why they’re not so right anymore. 

The disappointing part is that a lot of people still believe these things. 

Fat people should always lose weight.

Just because a person is in a bigger body, doesn’t mean that they’re at risk for disease (or that they WANT to lose weight). 

We used to just assume that big bodies were ticking time bombs, and that all fat people wanted to lose weight…because why wouldn’t they? We thought that skinny was healthy.

So wrong. Ugh. Hey, we also ate fat-free mayonnaise. It was a dark era.

We’re now learning that not everyone needs to be a size 6 to be healthy. In fact, people in big bodies can be just as metabolically healthy as their smaller-sized counterparts. Also: not every fat person wants to lose weight.

Also, putting someone on a weight loss diet because YOU think they’re fat, is shaming and gross. 

Every case is different, and now we know: never make a blanket assumption about a person’s health status because of the size of their body. 

I also want to take this opportunity to give you a term: ‘social determinants of health.’

This is something I learned about not in school, but after years of counselling people who couldn’t prioritize their health because they have no. money. to. buy. food. or. pay. rent.

This brings me to another thing we believed in those days: it doesn’t matter if a way of eating interferes with someone’s life or emotions, if they want to be healthy, they need to suck it up.

The way a person looks doesn’t always reveal their struggles. Assuming that everyone has access and ability to eat the way you think they should be eating, is a tone-deaf and privileged point of view. 

If a person follows a recommended diet that doesn’t fit with their lifestyle, they’re more likely to experience shame and guilt when they aren’t able to adhere to the plan. But that’s not their fault – it’s the fault of the practitioner.

Thankfully, in the decades since I’ve graduated, we’ve become more aware and inclusive of those people who are struggling with these things. The tough-love approach is so harmful and offensive to me now. It never works, and it’s destructive AF.

There are 3500 calories in a pound of fat.

I could probably write an entire post about this one.

While technically a pound of body fat may contain around 3500 calories, the entire concept of gaining weight by eating 3500 extra calories, or losing weight by creating a deficit of 3500 calories (often recommended as a daily deficit of 500 calories per day to lose a pound a week), is faulty. This rule was developed by Max Wishnofsky, MD in 1958, when we maybe didn’t understand the complexities of the body and metabolism the way we do now.

Calories aren’t created equal – we metabolize them differently from person to person, and caloric values of food may be inaccurate. Nutrition labels can be off by 20% either way, and again – we don’t know how many calories each of us actually ‘absorbs’ from food. 

We suspect that genetics, gut bacteria, and other factors have an impact on that.

(Read my post: Here’s Why Calorie Goals Are a Problem)

The 3500 calorie rule is usually used to justify cutting 500 calories a day to promote weight loss of a pound a week. 

The problem is that cutting 500 calories a day from your diet can result in not just fat loss, but also muscle and water loss. Someone with more fat to lose will likely lose weight faster than someone who doesn’t have a lot to lose. 

Most importantly, after you lose a certain amount of weight, you won’t need as many calories – rendering the 500 calorie number useless in estimating how much weight a person will lose over time.

BMI is a great way to determine someone’s health.

Speaking of weight loss and health, BMI was used (and still is, unfortunately) to determine someone’s health status. It can be useful, but only in conjunction with other metrics, not on its own. And only then, to see patterns – not to categorize someone as ‘obese’ or ‘normal.’ Yikes.

BMI was invented in the 1830s as a way to determine population health for resource allocation during the war, not as an individual health indicator. Even the guy who invented it said that it shouldn’t be used the way it’s being used today. 

BMI is faulty because it doesn’t take into account a person’s fat to lean mass ratio; their body structure (aka some people are just bigger than others); and the location of fat on their body. All of these can make a significant difference to a person’s health. But to BMI, it’s all the same. 

(Read more here about why I think BMI shouldn’t be used anymore)

weight loss

Margarine is ‘heart healthy.’

I’m guilty of saying that margarine is one molecule away from plastic. I now realize that was food shaming, and I wouldn’t say it now. But is margarine better than butter?

We thought it was…in the 90’s.

While margarine isn’t horrible or anything, we now know that eating for flavour and enjoyment is important to our well-being. For a lot of people, that means choosing butter over margarine.

In terms of the science, there aren’t any studies that suggest margarine is going to prevent cardiac disease when eaten instead of butter. Yes, butter has saturated fat, but how much butter are you really eating, and is the saturated fat in dairy products (like butter) harmful to health?

Research suggests it probably isn’t (check out this 2021 meta analysis on the topic here). On the other hand, margarine may contain trans fats, which we know are harmful to health. 

(Read my post: Are Seed Oils Harmful? here)

It comes down to this: eat a variety of fats, and choose the ones you like. Don’t over consume butter OR margarine. 

Too much protein causes kidney failure.

Remember Dr. Atkins? When I was in school, there was Dr. Atkins with his low-carb diet, versus Dean Ornish, with his ultra low-fat diet. 

We used to tell people that eating too much protein on the Atkins diet – because it was all bacon and eggs and cheese – that they’d cause irreparable harm to their kidneys. We stuck to the 0.8-1.0 grams of protein per kg of bodyweight rule for our recommendations.

Not anymore!

We know that in most cases, for healthy individuals, eating more protein is fine – 1.2-1.4 grams per kg can promote satiety and help to maintain lean body mass, especially in older adults. 

(Read my post, How Much Protein Do We Need Each Day? here)

There’s so much recent research around protein amounts and protein timing, which you can read about in my post linked above. Needless to say, we’re recommending more protein, not less, and talking more about spacing – something we never even thought about in the 90s.

You need dairy for calcium.

Dairy was always a part of the Food Guide/Food Pyramid, which in the past, we learned to follow for recommendations around eating.

What we didn’t learn, is that the dairy industry lobbied to be in that resource so people would consume their product. Classic conflict of interest.

Full disclosure: I love dairy foods. But I also tell people that you can live a very healthy life without them, and unlike what we learned in school, you can get calcium without ever drinking another glass of milk again.

I’m also suspicious about calcium recommendations in general: why do adults in the US need 1000 mg of calcium a day, but in the UK, the recommendation is only 700mg?

Surely we aren’t that different on this side of the pond.

Regardless, calcium can be gotten from fortified nut milks, tofu, leafy greens, seeds, and nuts, among other foods. 

Grains for days…aka low-carb diets are harmful to our health.

OMG the grains. We used to recommend that 8-11 servings of grain foods, which I would never do now, at least not as a blanket recommendation.

Grains are fantastic, and in no way do I think they should be vilified, but 11 servings is too much for most people. Theoretically, you could consume 11 pieces of bread and still be within those recommendations. 

Also: we treated everyone that same. Yipes!! We now know that some people do better with higher carbs, some lower. No big deal. And low-carb diets aren’t for everyone, but they aren’t likely to physically harm someone like we previously thought. 

The issue is not that starch is bad for you, but that those starches would crowd out other nourishing things in the diet. 

We’ve since taken the focus off starches and put them onto quality and balance, bumping up protein and vegetables and healthy fats and reeling in the carbs a bit.

I currently suggest a moderate carb diet, which works for most people. 

Sugar is ‘empty calories’ and you shouldn’t ‘waste calories’ on certain foods.

First of all, there is no such thing as ‘empty calories.’ Calling them that belies the fact that food is for more than just nourishment; it’s also for pleasure, community, culture, storytelling, love, and a whole lot more. 

Yes, some foods are more physically nutritious than others, nobody is disputing that. And yes, for optimal health, these foods – those of which you enjoy – should make up the majority of your diet.

But the belief that a food that brings you joy, is ‘empty’ and ‘wasteful’ can cause shame and guilt around eating, which isn’t productive and can be harmful.

We used to teach people that food is fuel. We now recognize that it’s so much more, and that that’s not only okay, it’s a good thing.

You should always eat breakfast. Otherwise, your body will go into ‘starvation mode.’

I’m finishing with this one, because my post on whether there’s such a thing as starvation mode has been super popular. (Read it here)

I actually used to advise people to eat breakfast ‘for their metabolism,’ even if they weren’t hungry. So to all of those people who might be reading this: I was wrong, and I’m so, so sorry.

When we know better, we do better, and I would not make that same recommendation today. 

You do NOT go into ‘starvation mode’ from skipping breakfast.

You do NOT need to eat breakfast if you don’t want to.

Breakfast is NOT the ‘most important meal of the day.’ That phrase was coined by Mr. Kellogg himself, in order to sell breakfast cereal. 

And lastly, please don’t eat if you’re not hungry, unless you have a good reason. For example, you might eat because you know you won’t have another chance for hours on end. But telling every person that not eating breakfast is ‘like trying to drive a car without putting gas into it first’ wasn’t correct.

Nutrition is always changing. It can be frustrating for the layperson (and often, dietitians!) to see changing recommendations, but know that they’re changing because we’re learning more and we know better than we did before. That’s a good thing.