The Shocking Math Behind Science Teacher’s McDonald’s Diet

McDonalds Dieter

Iowa science teacher John Cisna became a weight loss celebrity this week, after his “before and after” photos went viral online. It’s not that the pictures are anything special, the story behind them is. You see, Mr. Cisna lost 37 pounds over the course of 90 days, while eating exclusively at McDonald’s!

If this seems counter-intuitive to you, you are not alone. Cisna wanted to teach his students that it is not McDonald’s that is making people fat, it’s people’s choices. Together with his students and McDonald’s website – Full Menu Explorer – he planned his meals for 3 months worth of fine dining at a local franchise.

Weight loss can be achieved eating any food, as long there is a calorie deficit at the end of the day. Cisna consumed fewer calories than he exerted and therefore he lost the weight. The 54-year old teacher started out at 280 pounds, leading a sedentary life. He reduced calorie intake and added a dollop of exercise to drop his daily calories.

Just how much you ask?

To lose one pound of weight you need to create a deficit of 3500 calories. To lose one pound a week, you need to consume 500 calories less than usual per day, for 7 days straight. Or, you can burn 500 calories by walking briskly for 45-60 minutes.

To lose 37 pounds, Cisna had to reduce 129,500 calories from his diet!

That’s almost 1,500 calories less per day. At Cisna’s age and weight, the default caloric intake to maintain weight is 3,280 calories. To lose weight, he needed to subtract 1500. This means he would only be allowed to consume 1780 calories per day, basically halving his calorie intake.

Fortunately for Cisna, he exercised by walking 45 minutes 4 times a week, which created a 450-calorie deficit each time. Averaged out over 7 days, that works out to minus 250 daily calories. Cisna could eat approximately 1780+250 calories of McDonald’s fare each day, just about 2000 calories.

We’ve entered Cisna’s typical day’s worth of meals into Fooducate’s Health Tracker (available for free for iPhone and Android). This is what it looks like:

McDonalds Diet on Fooducate

As you can see, on the days he walked, Cisna was slightly under his calorie budget.

But what was the quality of the food he ate?

Here is the breakdown:

McDonalds Diet Nutrient Analysis on Fooducate

As you can see, the calories may have been in line with weight loss, but the food quality was not, which makes it even more surprising that Cisna also dramatically improved his blood cholesterol levels down from 240 to 179. High blood cholesterol levels increase the chances of heart disease.

A few thoughts:

1. First of all, kudos to John Cisna for losing weight and improving his cholesterol count. We’d also like to congratulate him for trying to teach his students about choices.

2. We would love to see Cisna’s blood pressure and other health parameters. You see, his meals exceeded daily sodium intake requirements by 100%!

3. Eating healthy and losing weight are not necessarily the same thing. The food at McDonald’s is ultra processed. Even with the healthiest choices, Cisna ingested artificial sweeteners, fillers and additives. The long-term heath effects of such foods are not good, even if no immediate symptoms are evident.

4. Eating and healthy and losing weight are about making the right choices. McDonald’s does offer a few healthy options, but if you look at the majority of their sales, they don’t come from apple slices and small fries. McDonald’s advertising, both in store and in the media, focuses on burgers, fries, and other unhealthy fare, which means the majority of people are not making a healthy choice. We are no weaker willed than previous generations were, but we are nudged by McDonald’s and other fast food companies to make the bad choices much more often than the good ones.

What’s your take on this experiment?

To track your calories and their quality, get the free Fooducate App (available for iPhone and Android).

  • John Cserkuti

    > Weight loss can be achieved eating any food, as long there is a calorie deficit at the end of the day.

    All calories are not equal I’m afraid and I keep seeing this bit of “advice” posted on nutrition and health sites. Different types of macro-nutrients go through different metabolic pathways and have different effects on the body.

    To our bodies there is no such thing as a calorie:

    • Fooducate

      Hi John, agreed. There is a growing body of evidence that not all calories are the same. But dropping 1500 calories from your daily diet would have an effect even no matter what you ate.

      • John Cserkuti

        > But dropping 1500 calories from your daily diet would have an effect even no matter what you ate.

        Agreed as well.

  • LeAnn @ Real Fit, Real Food Mo

    Glad to see this article. Yes, you CAN lose weight eating processed foods, but over time it’s definitely NOT the healthiest choice! Eating REAL food is always MUCH better!!!

    • Fooducate

      Right on

    • Dale

      I’d like to see all 90 days so it may be discerned if he ate the salad choices as well as the fruit options. Why was there no link to that info?

  • roger

    you can also drop cholesterol levels eating completely nothing, of course a caloric deficit will improve blood profile markers, but by how much will depend on quality diet and exercise.

  • Brittany

    Just because you CAN, does not mean you SHOULD.

    • kfay

      0% A, almost 200% sodium, 1/2 the fiber, and 79% HIGHLY PROCESSED. I have never felt better about my bad days than I do right now…

  • anthony

    This is true. You can lose weight while eating whatever you want but as long as you negate the total calories for that day. In my experience, when I was stationed on CVN76, the carrier, I used to always eat at the chicken wing line and the burger line. I’d always eat about a dozen strips of bacon for breakfast and some panckakes or waffles and maybe a boiled egg or two. Sounds little but I can put down some food. For midnight, it was the same thing. But the thing is, I was on a carrier in the middle of the sea and months from going home. I had nothing else to do but hit the gym a couple hours a day and do some cardio for about an hour as well. I also ate these 12″ hoagies they put out between meals often. My weight was always at 160lbs. I am 5’1″ I was big but not at all fat. I noticed when I transferred off the ship to a shore command, I gained 10lbs in 2 mos and 20lbs in 6! I had kept my eating habits from The ship but had not been as active as used to be! That’s how much being active can impact your body!

  • reachue

    Food is all about choices… Even processed foods!

  • SonyaL70

    I’m sure he could lose weight eating all candy bars, too. However, the contents of his choices via McDonald’s is a certain recipe for cancer, heart and vascular disease, among other risks. How short-sighted, albeit well-intentioned. Ultimately, he succeeded at advertising for McDonald’s and propogating the deception of the fast food industry. It’s like saying you can be healthier using arsenic as an alternative to strichnine.

  • Meme

    I think his point was dead on! Quit blaming everyone else for your problems and become accountable yourself! Whether it’s your diet, your health, your finances, etc., at the end of the day we are in charge of ourselves so stop blaming everyone else!

    • Fooducate

      Not as simple as that. Our choices are not made in a vacuum. When government policy and unregulated corporations make junk food cheaper than fresh fruit and vegetables, it steers choices in an unwanted direction. While some individuals will withstand the pressure to choose the cheaper options, the majority will be influenced to make the wrong choice. Our collective choices are not truly independent.

  • DarrylM

    This kind of “lesson”, from a committed teacher is one that the students will relate to. Choices are yours to make.

  • Charlie’sMom

    It also makes a difference what your genes are. Who knows – maybe this guy has great genes! I always ate horribly and was/am overweight (obese) but my cholesterol and blood pressure are excellent. No one ever takes genes into account. I have different genes than a supermodel, therefore, I have come to accept the fact that I will never look like one!!!

  • sdd

    Love this story, the movie “super size me”and the attention it received was silly.

  • Iowa Weight Loss

    First and foremost it is great that he is teaching his kids about choices. Weight is a complex subject but not matter what everyone has a choice to eat healthy. Good on you Mr. Cisna!

  • aaroncoal

    His point was to tell Morgan Spurlock to take a flying leap.. which he succeeded in doing. He’s not the only one. The guy who made the documentary Fat Head did the same thing and improved his overall health. The point is that slamming McDonald’s as an evil corporation is less about food and more about mindless liberalism and pro-government bullcrap.

  • Colt Soreno

    Guess what.. It’s also a fact that Cholesterol levels have NOTHING to do with heart disease. In fact studies have shown that people with lower cholesterol levels have a higher mortality rate from heart disease. I say kudos to this guy for losing weight. Liberals want everyone eating only organic gluten free pineapple from independent whole food markets run strictly by illegal immigrants. And then they can’t figure out why they go ahead and die of strokes and heart attacks anyway.

  • Jodin Jacklin

    Losing weight should be healthy.