“I always think crackers aren’t allowed.”

“I thought whole milk was bad.”

These are both things clients have said to me.

And neither surprised me.

Because if you’ve spent any time trying to lose weight over the past 20, 30 or 40 years, chances are you’ve accumulated quite a collection of food rules along the way.

Count calories. Avoid carbs. Choose fat-free. Eggs raise your cholesterol. Eating less is better.

Then along comes a GLP-1 and changes your appetite, but it doesn’t automatically erase decades of thinking about food.

One of my clients, Angela, described this shift beautifully:

“One of the biggest shifts for me was learning to let go of decades of diet thinking. For years I'd labelled foods as ‘good’ or ‘bad’. Carbohydrates, milk, fruit and other foods had become things I believed I should avoid if I wanted to lose weight. Anne-Marie helped me realise that nourishing my body was far more important than restricting it.”

I see versions of this all the time.

So let’s look at five old nutrition beliefs that have proved remarkably sticky, and whether they still deserve a place in the way we eat.

MYTH #1: I need to count calories to lose weight

First, what actually is a calorie?

A calorie is simply a measurement of energy. When we talk about the calories in food, we’re talking about how much energy that food contains.

And calorie counting is a pretty crude tool for understanding what happens to that energy once we eat it. Human beings aren’t Bunsen burners. We don’t all digest, absorb and use energy in exactly the same way.

BUT if we think about calories as energy, the basic principle still holds: to lose weight, our bodies ultimately need to use more energy than we consume.

That doesn’t mean you need to count every calorie that passes your lips.

And it certainly doesn’t mean the lowest-calorie choice is automatically the healthiest one.

Calories tell you how much energy a food contains. They don’t tell you whether it contains protein, fibre, healthy fats, vitamins or minerals, or how satisfying you’ll find it.

And when you’re taking a GLP-1 and eating considerably less, I’d argue those things become more important, not less.

The goal isn’t simply to get as few calories in as possible. It’s to make the food you are eating count.

MYTH #2: Carbs make you gain weight

Two clients have said things to me recently that made me sad:

“I always think crackers aren’t allowed.”

“I haven’t eaten pasta in years, even though I love it.”

Years!

Bread. Crackers. Potatoes. Rice. Pasta. For decades, carbohydrates have been high on the list of foods we’re told to avoid if we want to lose weight.

But “carbohydrate” isn’t a synonym for “unhealthy” or “fattening”.

Fruit contains carbohydrates. So do oats, lentils, chickpeas, beans, wholegrains and potatoes. These foods can also give us fibre, vitamins, minerals and a whole lot of nutritional value.

And eating pasta doesn’t somehow override the basic energy principle we just talked about.

Rather than asking:

“Am I allowed to eat carbs?”

I’d much rather you asked:

“What is this food bringing to my diet and what could I eat with it?”

Those crackers could be topped with tuna, cottage cheese or hummus. Pasta could come with chicken or lentils, loads of vegetables, olive oil and parmesan.

The carbohydrate isn’t the problem simply because it’s a carbohydrate.

MYTH #3: Fat-free means healthy

Another client, Angela, told me:

“I thought whole milk was bad.”

Oh, the low-fat years!

Skim milk. Fat-free yoghurt. Low-fat cheese. Fat-free salad dressing.

Many of us learned to equate less fat with healthier.

But removing fat from something doesn’t automatically make it healthy and the presence of fat doesn’t automatically make it unhealthy.

Olive oil, nuts, seeds, avocado and oily fish all contain fat. Dairy foods can absolutely be part of a healthy diet too.

The bigger picture matters: what type of fat, what food it comes packaged in, what else that food provides, and what the rest of your diet looks like.

A tub of full-fat Greek yoghurt, for example, brings protein, calcium and other nutrients along with its fat.

You can’t judge the nutritional value of a food from one number on its nutrition panel.

MYTH #4: Eggs cause high cholesterol

Remember when eggs were practically nutritional villains?

Our understanding of dietary cholesterol has become much more nuanced since then.

Eggs do contain cholesterol. But for most people, the cholesterol we eat has a smaller effect on blood cholesterol than we once thought. Our overall dietary pattern, including the amount of saturated fat we eat, matters too.

Meanwhile, eggs are a nutrient-dense, compact source of high-quality protein, along with a range of vitamins and minerals.

And if you’re on a GLP-1 and finding larger meals difficult, compact sources of nutrition can be particularly useful.

So no, having eggs for breakfast doesn’t automatically mean you’re giving yourself high cholesterol.

MYTH #5: Losing weight automatically means my diet is healthy

This may be the most important one if you’re using a GLP-1.

It’s very easy to assume that if the scales are moving in the direction you want, what you’re doing must be working.

But weight loss and good nutrition aren’t the same thing.

You can be losing weight and not getting enough protein.

You can be losing weight while eating very little fibre or few plants.

You can be losing weight while missing important vitamins and minerals.

And you can be losing weight while losing lean tissue, muscle and bone as well as body fat.

The scales tell you what’s happening to your body weight. They don’t tell you how well you’re nourishing your body.

And this is one of the reasons I keep banging on about protein, plants, fibre, strength and making the food you are eating count.

Maybe it’s time to rewrite some of the rules

Nutrition science evolves. But the messages many of us absorbed during years of dieting can be remarkably hard to shake.

And that’s something I find particularly interesting about GLP-1s.

Your appetite can change very quickly. Your thinking about food can take much longer to catch up.

But perhaps that’s also part of the opportunity.

When the food noise becomes quieter, there’s space to question some of those old rules.

Do I really need to avoid potatoes?

Is full-fat yoghurt actually a “bad” food?

Do I need to know how many calories are in everything I eat?

Is the number on the scales the only measure of how well I’m doing?

Because the goal isn’t to become exceptionally good at restriction.

It’s to learn how to nourish your body in a way you can carry forward.