Can I Eat McDonald’s On a Calorie Deficit?

One of the first words my clients use to describe themselves. Busy, rushed and stressed out. That’s why eating out is sometimes the only option. In this article I will explain everything you need to know about McDonalds and calorie defict.

Can I eat McDonalds on a calorie deficit?

In general, you can eat Mcdonald’s on a calorie deficit. During busy times with no access to homemade food, it is acceptable to eat at the food outlets. The takeaway meals are convenient. However, they are too high in calories and too low on fiber to be part of the regular calorie deficit diet.

It’s even beyond the calories or the fat content.

Food that we eat literally affects our brain, mood and energy.

Does McDonalds Make You Gain Weight?

In general, McDonald’s does make you gain weight. Most of the meals from popular food outlets contain high-calorie dense foods with not enough fiber, vitamins, and minerals. Foods that are high in sugar, fat, and low on fiber can lead to decreased satiety and overeating.

Eating Mcdonald’s on a daily basis is correlated with weight gain. In fact, after researching data for this article, I found that the number of Mcdonald’s restaurants is related to the prevalence of obesity (source).

Also, it shows that the presence of fast-food restaurants contributes to the greater prevalence of obesity in deprived neighborhoods (source).

But let’s be realistic.

Human behavior also plays a role.

So we cannot blame the obesity only on fast-foods.

Just because it’s there, it doesn’t mean we have to go there.

Related article: 5 Ways To Be In A Calorie Deficit Without Being Hungry

How Much Weight Can You Gain From Eating McDonald’s?

Over the 12 months’ time, you can gain 26 kg of body fat from eating one big mac (550 calories) every day on top of your regular calorie intake. Eating one cheeseburger (300 calories) every day can add an extra 14 kg of body fat, and 24 kg from one vanilla milkshake (510 calories).

There is more.

  • Chocolate shake 520 calories
  • McCafe 220 calories
  • McMuffin 310 calories
  • Double Quarter Pounder 720 calories
  • Fries 220 calories


I could eat at least 2-3 burgers and wash it with extra large milkshake.

Without any effort.

Because those meals are full of fat, salt, cheese and sugar, you cannot stop eating.

Which is really the problem.

Does McDonald’s Make You Fat?

As a whole, Mcdonald’s can make you fat. Foods that contain low fiber and a high amount of calories can lower satiety signals, increase appetite, and trigger unwanted overeating behaviors. Overeating any high-calorie dense food can lead to higher body fat.

Which is nothing novel.

Because overeating on any food leads to calorie surplus.

And weight gain.


When it comes to calorie deficit, it really doesn’t matter what you eat.

As long as you stay in negative energy balance.


Can you lose weight on McDonalds?

Can You Eat McDonald’s And Lose Weight?

As a whole, you can eat Mcdonals and lose weight, as long as you stay within a calorie deficit. Calorie restriction works regardless of the method or the food you consume. However, long-term consumption of fast-food can lead to poor nutrition, low energy, and mood problems.

In other words.

You can eat McDonalds and lose weight, but you need to eat only one to two burgers per day.

That’s it.

Which is definitely not my cup of tea to be honest.

But I’ve seen few people who tried eating one big mac per day.

Can I Eat a Big Mac And Still Lose Weight?

You can eat big mac and still lose weight. One big mac has 550 calories. Eating only one to two big mac’s per day (and nothing else) can cause enough calorie deficit to lose weight.

There are many YouTube videos of people experimenting with McDonalds.

My favourite one was from Jordan Syatt.

He eat one big mac everyday for 30 days.

And he lost 7 lbs.

The secret?

That’s all he ate.

So he was in a good calorie deficit.

Which shows you can eat McDonalds and lose weight.

But this experiment wouldn’t last for more than 30 days.

Because living on McDonalds is not sustainable.

Why Eating McDonald’s Is Bad For You?

Eating Mcdonald’s is bad because fast foods don’t contain valuable nutrients. The only way to sustain a healthy diet is with nutrient-dense foods, high-fiber foods, and consistency. Infrequent consumption of low-quality foods is acceptable but is not sustainable in the long term.

High-fiber foods.

Nutrient dense foods.

This is the golden recipe for optimum health and performance.

  • Nutrient dense foods

Nutrients dense means food packed with macro and micro nutrients.

Those are your high-quality proteins, unprocessed fats, vitamins, minerals and phytochemicals.

All of them play a role in our metabolism.

  • High fiber foods

There is a whole shebang of benefits from eating foods that are high in fiber.

Beyond weight loss.

It helps with poop.

And with gastrointestinal health.

And with overall health issues like diabetes, obesity and blood pressure.

High fiber foods not only increases the satiety.

But it also affect the gut microorganisms (more on that later).

Can You Lose Weight Eating Only McDonald’s?

As a general rule, you can lose weight eating only McDonalds. In the short term, losing weight can happen after any dietary approach. However, to promote good health and maintain reasonable results for the long-term, eating only fast food is not the best idea.

This goes even beyond weight loss.

There is a connection between gut and the brain.

It’s called GBA (gut-brain axis) (source).

It’s a marriage of central nervous system with enteric nervous system.

Everything what you eat affects microbiota (microorganisms in your gut).

And those microorganisms influence rest of the body. They can affect:

  • Emotions
  • Thoughts
  • Sleep
  • Social behaviors
  • Stress response
  • Feelings
  • Hormonal balance
  • Cognitive functions

Recent studies show a link between our gastrointestinal tract microbiota and signs of depression, anxiety, and mood disorders (source).

In other words.

The more nutrient-dense food you eat, the better your microbiota.

The better you feel.

This can have a positive impact on your:

  • Work
  • Health
  • Performance
  • Learning
  • Relationships

But if your food is chronically low in nutrients and high in refined sugar.

Then not only it will cause your weight gain.

But the whole avalanche of negative thoguths, feelings, worries, and self-talk.

Eating McDonald’s Everyday And Working Out

Eating McDonald’s everyday and working out is much more common around the physically active people.

Especially professional athletes.

And you would thought that people who train hard must be watching what they eat, right?

Not really.

Just look up on Instagram.

Athletes from the NFL or NBA gobbling on McDonald’s without any regret.

In fact, a lot of the NBA players eat worse than the average person from the street.


  • They have good genetics
  • They have strong mentality
  • The put in crazy amount of work into the gym

So they literally thrive, despite eating shit.

Not because of eating shit.

They can eat whatever they want.

They are not doing calorie deficit.

But for everyone else.

For me and you.

We are not blessed with the genetics of world-class athletes.

So we have to watch what we eat if we want to stay lean.

Which is not fair.

But that’s they way it is.

Is It OK To Eat McDonald’s While Working Out?

It is not recommended to consume any food while working out. During the physical activity, there is an activation of a sympathetic nervous system, and blood is pumped into the muscles. As soon as you start to eat, all the blood is flowing into the digestion to start breaking down food.

What’s the healthiest option at McDonald’s?

The healthiest food in the McDonald’s include apple slices (15 calories), low-fat milk jug (100 calories), ice tea (90 calories), chicken nuggest (170 calories) and water.

To be honest.

Does anyone ever orders apples from McDonalds?


Eating Mcdonald’s while being in a calorie deficit (from time to time) is acceptable.

What is not acceptable is eating there every day, just because it’s convenient.

Because not only you can stall your weight loss.

But also it can have a huge impact on the gut health and the mental health.

Michal Sieroslawski

Michal is a personal trainer and writer at Millennial Hawk. He holds a MSc in Sports and Exercise Science from the University of Central Lancashire. He is an exercise physiologist who enjoys learning about the latest trends in exercise and sports nutrition. Besides his passion for health and fitness, he loves cycling, exploring new hiking trails, and coaching youth soccer teams on weekends.

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