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10 Calories in, 1 Calorie Out – The Energy We Spend on Food

The views expressed are those of the author and are not necessarily those of Scientific American.

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In December, I attended Michael Pollan‘s lecture at the University of Texas’s Bass Concert Hall. My friend, Katie, had called me that morning to ask if I would be interested in joining her for the lecture – she knew that I had read three of Pollan’s books on food and had also found out that there were $10 student tickets to be had for the lecture. Long story short at 7:40pm I found myself zipping down Guadalupe with Katie for my first Bass Concert Hall event in my tenure at UT.

Pollan’s lecture was interesting, engaging and funny. This was not surprising to me, after having read his books. The bags of groceries that he brought from the Fiesta across I-35 brought in the usual laughs (“Venom” who knew it was a drink??) and groans (Twinkies… ahh, the infamous Twinkie).  But, of all the things that he said about “food-like substances” – the things that trick you into thinking that they are food, but have very few similarities with the real thing – and the problems with the Western diet, the thing that stuck in my head was the following….

10 calories in, 1 calorie out

According to Pollan, for every calorie of food that is produced in the United States, 10 calories of fossil fuel energy are put into the system to grow that food. By no means a break-even system.

I was chewing on this factoid as we left the lecture, musing through how our agriculture industry works today. We grow food – corn, wheat, sugar – and, while some of it grows wild and free with no inputs beyond sun, water and the nutrients that the soil provides, the majority of the food that we produce requires significant energy inputs from us.

And, even after this food is produced (at an energy cost of 10:1), most of it does not come to our tables in its whole, natural form. Instead, the majority of this food is sent to a plant for processing into what Pollan likes to call “food-like substances” (at an additional energy cost). For the purpose of this post, I won’t get into what is and is not food – feel free to check out his books to explore this concept – but I would like to discuss the idea of putting more energy into our food than we are getting out of it.

10 calories in…. 1 calorie out…

If I am like the rest of the US, my household will throw away 1.5 pounds of this energy intensive food each day. While this pound and a half might seem small, when totaled over a year (and over the 300+ million people that live in the U.S.) these pounds represent a huge amount of wasted energy. Today, the food that Americans throw away represents approximately 2% of the energy we use in this country. That’s enough embedded energy to power two Switzerlands.

And, when looking at the content of the food that we eat and waste, we see another interesting trend. Over the past four decades our tastes in food have shifted – away from coffee, eggs and milk to more sweet and fatty foods.

As Michael Pollan pointed out in his lecture, this shift in what we eat has led to high levels of obesity and all of the associated health risks (diabetes, high blood pressure,…). And, simultaneously, our agricultural systems have evolved into an energy intense food system where we spend 10 calories for every 1 calorie that we produce. A lot of food. A lot of energy. A lot of waste. Doesn’t sound very sustainable to me.

[Bora Zivkovic posted a review of one of Michael Pollan's books, titled the Omnivore's Dilema, on his "Blog Around the Clock" today.]

Picture Credit:

  1. Photo of Michael Pollan pouring “black gold” © by Kevin Krejci and used under this Creative Commons license.
  2. Photo of cropland © by Tobyotter and used under this Creative Commons license.
  3. Food waste picture by Nick Saltmarsh and used under this Creative Commons License
  4. Chart from the USDA

[A version of this post was originally published on December 10, 2010]

Melissa C. Lott About the Author: An engineer and researcher who works at the intersection of energy, environment, technology, and policy. Follow on Twitter @mclott.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. joshdr83 10:43 pm 08/12/2011

    That food waste looks to be about 6 weeks from good compost!

    That might be an interesting study, to look at the artificial fertilizer that might be replaced with composted food waste.

    Link to this
  2. 2. acuellar 9:08 am 08/16/2011

    Hi Melissa,

    I’ve been keeping up with your Scientific American blog, and I’m really enjoying it! I recently read your post about food and energy, and I think it’s great that you’re bringing to light how energy intensive modern agriculture is. Although, I think your readers may need a little more context to really understand what the 10:1 number means.

    1. First off, I think a brief outline of the history of agriculture would really help your readers understand why we use so much energy in modern agriculture. The energy intensity of agriculture has changed over time, and the greater use of fossil fuels for many agricultural tasks have made food production and procurement much more convenient. Fossil fuels in the agriculture system have decreased the need for human and animal labor and allowed for greater yields per farm worker, area of land, and farm animal. This means that less of us have to dedicate our labor to procuring food and can dedicate ourselves to other tasks. In some agriculture sectors this has also meant less negative impacts on the environment. Agriculture will always require some level of energy input, so the question is what source do we prefer? In making this decision we must also consider the power we can obtain from each energy source; fossil fuels have enabled us to achieve tasks that are simply not possible using human or animal labor. I actually just saw a USDA paper that stated that total energy use in agriculture (not the entire food system) peaked in 1978, which suggests that energy efficiency in agriculture may have increased in recent years.

    2. Also, we should consider energy quality when comparing fossil energy to food energy, as in the 10:1 ratio. Food is our only source of nourishment and contains more than just energy, we also get nutrients, vitamins, minerals, essential amino acids, etc. from our food.

    3. It may also help your readers to know if the 10:1 number is an average (I imagine it is) and how different foods measure up in terms of energy requirements. My previous work quantified these differences. Also, how many calories do we consume (or are available, because we don’t consume them all) annually in the US? (I think it’s over 3,500cal/person/day) How much energy does this amount to if we use 10 cal to produce every calorie available per person in the US and how does it compare to other activities? (I’ve seen estimates from 10-20% of US annual energy consumption is dedicated to food production)

    4. It is my understanding that the profit margin for agricultural products is actually quite small. Consumers want to pay the lowest price possible for food and, in order to maximize their profit, farmers must in turn maximize their production to achieve economies of scale. Therefore our demand for cheap food in large volumes incentivizes farmers and ranchers to produce as much food as possible and not to maximize energy efficiency. Although it may seem logical to solve the problem by creating efficiency incentives for food producers that may raise prices, we must also think about the large amount of people that can barely afford food at its current price (a billboard told me the other day that 1 in 6 Americans is hungry!). The people I have spoken to about this issue argue that farmers would supply energy efficient food if there were a market for it, but at the moment a large portion of the American public demands inexpensive food. Cheap food has been a good thing for this country for a long time, it has allowed us to live comfortable lives knowing that we don’t have to worry about whether we can afford to eat dinner. Whether cheap food continues to be a good thing for the American population is a question that is up for debate.

    5. Finally, I think the big question your readers and our society must consider is how much fossil energy do we want to dedicate to food production? What would shifting this average mean? The simple answers are probably changing what we eat, eating less and wasting less food, as you mention in your post. Larger cuts in energy for agriculture may require us to dedicate more labor to food procurement, accept not having certain foods available at certain times of the year, or spend more on food. In economic terms, this would affect our achievable utility. In short, how much convenience are we willing to give up to lower the energy intensity of agriculture? I don’t think there is a good or bad answer to this question, rather it is a choice we must make knowing the consequences and mindful of how it will affect all of society.

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  3. 3. Melissa Lott 2:14 pm 08/16/2011

    @acuellar – Thanks for your thoughtful comments. I agree that this is a rich topic, full of lots of tradeoffs and very real potential consequences. I certainly expect that we will continue to discuss different nuances in the future, because there are so many pieces to consider.

    You are right – the 10:1 number is supposed to be an average. In the post, I indicated that this number was a factoid because Pollan’s source is not 100% clear (he didn’t give a citation at the talk).

    What is clear, as you mentioned, is that we invest energy (and fossil fuels) into growing enough food to satisfy the needs of a large population. Which brings us to the question of, when does “a lot of energy” become “too much energy” – not an easy question to answer without some in depth analysis.

    Again, appreciate your comments. I’m glad that you enjoy reading the blog.

    Link to this
  4. 4. J4zonian 10:38 pm 08/16/2011

    A little booklet called Energy and Order (out of print but available used) that I used as an environmental educator has some activities that deal with this kind of thing for high school level education (easily adaptable up or down). One used the information from Roy Rappaport’s ‘Pigs for the Ancestors’ and studies by one of the Odums to compare the efficiency of “primitive” horticulture to our magnificent folly of a system. Way, way less efficient, and so doomed.

    Get out while you can.

    And if you think 10:1 is inefficient, take a look at the calories in the food vs. the calories in the package…

    Link to this
  5. 5. Melissa Lott 10:58 pm 08/18/2011

    @J4zonian – thanks for the recommendations

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  6. 6. jeff1937 12:12 am 12/21/2014

    The hyperlink “10 calories of fossil fuel energy are put into the system to grow that food” goes to a commercial composting company website, with no direct relevance.
    Where is the evidence for this statement ?

    Link to this

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