Getting Shredded On Junk Food
Obviously, trying to get shredded eating McDonalds every day is not the optimal way to diet.
This post is not meant to assert that you should diet down eating McDonalds every day, it is simply meant to illustrate how the metabolism works, and how daily calorie intake relative to daily energy expenditure is ultimately what will determine if you lose fat or not.
McDonalds food is not micronutrient dense.
It also doesn't have good macronutrient ratios in terms of protein relative to fat content.
With that being said, if you really wanted to, there's no reason why you couldn't lose as much fat as you want while still consuming McDonalds every single day.
And the fundamentals of each essentially boil down to calories in versus calories out.
You have a certain amount of calories your body expends on a daily basis.
This is determined through your Basal Metabolic Rate (BMR), coupled with your activity level.
You can figure this out with a maintenance calorie calculator, which calculates how many calories you can eat per day to keep your weight exactly the same.
By calculating your BMR (basal metabolic rate) factored in with however much physical activity you're doing on a weekly basis, you can figure out roughly how many calories you burn per day.
Once you know this figure, you can calculate exactly how much calorie restriction will be necessary to start losing fat.
If you want to lose weight, you have to eat less than this maintenance number.
Counting Calories Is The Most Important Thing You Need To Do
The reason why somebody would have trouble losing weight eating McDonalds is not because it's crappy junk food, but because it's calorically dense.
Most people don't count how many calories they are eating on a daily basis, which often leads to overconsumption.
Most people view their diet in terms of quantity, as opposed to how many calories are in the food they are eating.
For example, a junior chicken from McDonalds is 370 calories.
If you ate 3 of these per day, that would be an additional 1,110 calories per day, which isn't insignificant for the amount of food you are consuming.
Visually, it doesn't look like much, as 3 junior chickens probably only have about six to eight ounces of total chicken in them.
However, the way they bread the chicken, the unhealthy oils they cook it in, and the sauce they cover it in, all add hidden calories that you may otherwise not be considering.
At a first glance, many people would assume that they are eating the equivalent of a few ounces of chicken (90 calories) with lettuce (almost 0 calories), a bun (maybe 100 calories), and a bit of sauce (maybe 50-100 calories).
An uneducated guess would probably be closer to 250 calories.
And most wouldn't even bother to look at the nutrition facts anyways.
It's not very satiating, and can start to push your daily calorie intake up pretty high without you even noticing.
People gain weight eating junk food by over-consuming, not by eating junk food itself.
Hypothetically, if the maintenance calorie calculator says the amount of calories you expend per day is 2800, and you ate 1110 calories of those via junior chickens, you now only have 1690 calories that you have to fill with other things until you reach your maintenance.
Ensure that you're eating less than those 1690 calories if you want to have any chance of losing weight.
If you eat at maintenance or above it, your body will store the excess as either fat or muscle.
If you are in a deficit, your body will dip into stored energy to make up for that deficit to reach your maintenance.
If you ate 2600 calories with a 2800 calorie maintenance, your body has 2600 calories (energy) to fuel your activities and your everyday physiological functions on that day.
Your body will dip into your stored energy (fat stores or muscle tissue) to make up for those 200 calories that it is no longer getting from food consumption.
Restricting Your Calorie Intake Will Result In Fat Loss, Even If You Eat McDonalds
Through this process of caloric restriction, you can effectively burn fat off your body until you're as lean as you want.
A calorie deficit can also be achieved via cardio, weightlifting or whatever your favorite way of expending energy is.
Ideally you would utilize a combination of slow, tapered caloric restriction, and slow tapered increases in energy expenditure via physical activity.
Don't restrict yourself too much too quickly though, or else you will end up in a position where you can't lose weight even when you're eating as little as your girlfriend's maintenance.
At the end of the day, it's a game of calories in versus calories out.
You have to eat less than your body expends or else you won't lose weight.
It is possible to lose weight literally only eating chocolate or ice cream every single day as long as the calories of everything you ate during that day add up to less than what your body expends.
It should go without saying that I do not recommend this whatsoever, as it is not even close to optimal for muscle retention or health.
I know some guys who eats cheeseburgers every day as part of their diet.
They need that little treat in there to help them stick to their diet.
Is it ideal? No.
However, if it is the only way you will adhere to a diet, then in some cases it can be more beneficial to eat a bit of junk every day to ensure you stick to your daily calorie allotment.
Diet adherence and being oblivious to the importance of counting calories is the number one reason why most people fail trying to lose fat, and keeping it off.