This concept is simple but can take a little bit of planning to get it right. During normal daily activity (assuming this is non strenuous, walking, driving, desk job, etc.) you burn a set number of calories per hour based on your basal metabolism.
If you eat less calories than this you will not have enough calories for normal body function and will feel hungry. If you eat too much you will go into your next meal before your hungry and most likely eat more than you need for your next meal and repeat this process for dinner finally exceeding your total calories needed for weight loss for the day.
If you have strictly defined times you know you will eat your next meal plan on eating enough calories to actually make it there without starving by the time it is lunch and you decide you better get that large fry to settle the hunger.
Here is a real life example:
5’ 10” male at 193 lbs. and burns about 100 calories per hour with normal non strenuous activity.
- 7:00 am: Wake up
- 7:30 am: Eat breakfast (3 egg spinach and cheese omelet) – 370 calories
- 8:00 am: Remember in training today and will not be able to eat until 12:00
- 8:02 am: Eat a spoon of peanut butter – 95 calories
- 12:00 pm: Eat lunch (cheeseburger no bun) – 463 calories
- 5:30 pm: Daughter has birthday party probably no good food options
- 5:31 pm: Have snack to hold off until an expected later dinner (choco/peanut butter protein cookie) – 195 calories
- 7:00 pm: Dinner (double cheeseburger from McDs w/o bun) – 280 calories
- 10:00 pm: Go to sleep
As you can see I always kept myself at a calorie equilibrium based on the expected and unexpected events that occurred during my day. Using snacks not as a way to feel better between meals but to extend meals as plans changed. Even though for a 193 pound man I did not eat a lot of calories I did not feel deprived during this day.
The graph below shows my calorie surplus and it drops about 25 calories every 15 minutes. As you can see I carefully kept myself at a surplus during most of my waking hours to only go into a deficit when I go to sleep.
Now compare this to having a light breakfast (bagel or bowl of cereal) then be starving by lunch and go for the fries with the burger. Then eat a typical dinner, much more calories and the feeling of being stuffed almost all day (except for lunch when it was time to gorge) and very little time in a deficit to actually burn some fat as fuel.
Planning ahead and ensuring you are feeding yourself with good amounts of food can make creating a calorie deficit much more sustainable and increase your chances of success.