Daily Calorie Intake in the US from 1970-2010

Being someone who spends a lot of time in front of computers, I've led a more or less sedentary lifestyle for the past decade. Except for commuting mostly by bike, regular physical activity did not play a major role in my life. I set out to change that by the end of last year and started working out 3 to 5 times a week.

While physical activity is important for a healthy lifestyle, a healthy diet is a major factor as well. Part of the latter is not to take in more calories than you expend, unless you want to gain muscle/weight, and a balanced composition of macronutrients, i. e. proteins, fats and carbohydrates.

Due to my raised awareness of the importance of nutrition and my interest in data I recently came across food availability datasets provided by the U.S. Department of Agriculture Economic Research Service (USDA ERS). One of them (XLS-file) contains a breakdown of average daily calories by food group available per capita in the US from 1970 to 2012.

While availability does not equal intake, the data is adjusted for loss due to spoilage and other waste and serves as a proxy for actual consumption. To visualize how calorie availability/intake has evolved during the past 4 decades I created the stacked area chart below.

Average daily per capita calories in the US, 1970-2010

The chart does not include the years 2011 and 2012 because the data is incomplete. Moreover, in 2000, the number of firms reporting vegetable oil production to the Census Bureau increased, which contributed to the spike in the data for added fats & oils, and thus total calories from all foods.

What we can see is that the total amounts of calories per capita increased from 2,077 in 1970 to 2,590 in 2010, in other words about 500 calories more per day. This is a lot considering that 3,500 calories is roughly equivalent to 1 pound of body fat and that the average US citizen is presumably less physically active now than in 1970.

The two food groups contributing the most to the increase are Flour and cereal products and Added fats and oils and dairy fats, specifically Salad and cooking oils which increased from 115.5 to 402.3 calories per day in the observed time frame.

It shouldn't come as a surprise that the increase in calorie intake correlates well with the increasing prevalence of overweight and obesity, as the graph below shows.

Total Calories vs. Obesity Prevalence
Source: Calorie Intake and the US Obesity Epidemic by Stephan Guyenet

This development of people becoming less active and eating more, often enough unhealthy food is dramatic and affects many countries, not just the US. We should not go on like that. From my own experience I can only urge people to become more active and become aware of what they eat to improve their health and the quality of their lives.

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