Calories In vs Calories Out (also referred to as CI = CO or just CICO) refers to the idea that in order to maintain a steady weight the amount of calories eaten (food) must equal the amount of calories burned through basic metabolism (BMR), digestion, and physical activity.
This concept is strictly true. There must be a calorie deficit to lose weight. A person who is starving (does not have enough food to eat) will lose weight and eventually die. Nevertheless, the question considered in this post is whether this formula can be used as an effective guide to healthy, sustainable weight loss.
If the mathematical formula CI = CO is true and could be strictly followed, then it should account for these facts:
1.As of 2014 the average American ate 3770 calories/day. (The 2019 calorie average/day is probably higher.)
2.The average man needs to eat 2500 calories/day and the average woman needs to eat 2000 calories/day to maintain a constant weight.
3.One pound of body fat equals approximately 3500 calories.
4.Calories consumed and calories burned are the only variables that determine weight loss or gain.
5.To be successful as a lifestyle, any type of eating plan (diet) must be sustainable and healthy in the long run. Starvation is not a desirable, healthy, or sustainable long-term solution.
6.There is no simple and accurate way to determine the actual calories any one unique individual eats or burns each day.
These additional factors should also be considered:
1.Some individuals can reduce the amount they eat (number of calories in) and lose weight. However, most of the weight lost is regained once regular (non-starvation) eating patterns are resumed.
2.The average American is 30 – 50 pounds overweight. Since the average American eats 3770 calories/day, the average man would need to reduce calorie intake by 1270 calories/day (33%) and the average woman would need to reduce calorie intake by 1770 calories/day (47%) just to maintain their current weight.
3.Since one pound of body fact equals approximately 3500 calories, the average man eating 3770 calories/day would gain 132/lbs./yr. [(3770 – 2500 = 1270, 1270 x 365 = 463,550 excess calories/year, 463,550/3500 = 132 lbs.)]. The average woman eating 3770 calories/day would gain 184/lbs./yr. [(3770 – 2000 = 1770, 1770 x 365 = 646,050 excess calories/year, 646,050/3500 = 184 lbs.)]. Each year, every year!
Because CICO does not account for all these factors, it seems obvious that CICO is not a workable solution for healthy, sustainable weight loss.
Our bodies are amazing, self-regulating, biochemical factories. In order to survive over hundreds of thousands of years we have evolved to store excess calories in good times so that we don’t die during lean times (winters, famines, etc.). If we consistently eat more calories than we burn, the body stores calories as fat (adipose tissue) and our metabolism (the number of calories we burn) also increases.
On the flip side, when we eat less than we are accustomed to, (33% or 47% just to maintain our weight, our body interprets that as starvation and will reduce our metabolism. If calorie intake is reduced enough to compensate for the decrease in metabolism, the body will start to burn its fat stores and we begin to lose weight.
In order to understand more about how to lose weight and how to maintain a consistent healthy weight, the next post will begin to examine in greater depth the physiology of weight gain and weight loss.