Watch Your MealEnergy Analysis of Vegetarian and Non-vegetarian diets

Sahil Aggarwal

Objectives

• To estimate the energy requirements and carbon emissions in a meal

• To compare these values for vegetarian and non-vegetarian diets

• To suggest beneficial measures

Key Terms• Life cycle input

• Dietary energy

• Feed conversion ratio

• Water requirements

• Land requirements

Need and relevance• Growing food and cooking are energy intensive. They

also release greenhouse gases like CO2.

• Meat requires more energy than plants for growth and cooking for the same amount of calories yielded.

• Livestock sector generates more greenhouse gases as measured in equivalents of CO2 than transportation.1

• The data shown is substantial to indicate that a change in diet patterns is required to feed the growing population and reduce environmental damage.

Carbon Emissions• Carbon footprint of a food product is the total

amount of CO2 and other greenhouse gases emitted over the life cycle of that product or service, expressed as kilograms of CO2 equivalents.2

• Calculations for three food products – beef, chicken and beans – are shown below. It does not account for emissions due to transport. Comparison is not adjusted for the energy and nutrient output of different products.

Carbon Emissions

Beef Chicken Dry beans

Emissions calculated for producing 1 pound of commodity.Source: http://www.foodemissions.com/foodemissions/Calculator.aspx

Water requirements

Foodstuff Quantity Water consumption, litresChocolate 1 kg 17,196Beef 1 kg 15,415Chicken meat 1 kg 4,325Rice 1 kg 2,497Pasta (dry) 1 kg 1,849Bread 1 kg 1,608Potatoes 1 kg 287

Source: IME (Institute of Mechanical Engineers)

Land Requirements• Different products have different requirements of land

to grow the same amount of food. The figures shown below are indicative of the huge differences in growing different items.

• University of Groningen and Open University of Netherlands developed a method to calculate land requirements relating to food consumption patterns.3

Source: A method to determine land requirements relating to food consumption patterns, Elsevier, 2002. The land requirements are for Netherlands in 1990 taking household population as 2.41 persons per house and consumption data from Central Bureau of Statistics (CBS) report.4

Item

Land required

(m2/household)

Meat 1022Oils and fats 827Milk and eggs 598Beverages 368Bread 183Vegetables and Fruits 168Flour products 68

Food Chain Losses• Lineman proposed that only 10% of the energy is

available as we move from one trophic level in food chain to another. Plants absorb 1% of the solar energy received.5

• By this law, if plants receive 1000J energy, 10J will be available to herbivores, 1J to carnivores.

• Since secondary foods such as chicken, pork etc. take their energy from plants, it is important to check their Feed Conversion Ratio (FCR). FCR is the mass of food eaten divided by the body mass gained for the animal. Lower FCR means more effecient feed users.

Adjustment for nutritional output• Comparisons shown till now did not account for

the difference in output of various products. Therefore, while meat may require more land and water for growth, it might also provide more energy that balances the resources required for growth.

• Now we shall adjust the land, water and carbon emission values using the nutritional data from twofoods.com, an online portal to compare different food items.

Carbon emissions (adjusted for calories)Item CO2

emissions (per kg)

Calories produced per kg

CO2

emissions per 1000 calories

Beef 7.38 kg 2871 2.57 kg

Chicken 1.70 1950 0.87 kg

Wheat 0.3 1980 0.151 kg

Dry Beans 0.4 1861 0.214 kg

Carbon emissions (adjusted for proteins)Item CO2

emissions (per kg)

Proteins produced per kg

CO2

emissions per kg protein

Beef 7.38 kg 262.8 g 28.08 kg

Chicken 1.70 kg 295 g 5.76 kg

Wheat 0.3 kg 74.9 g 4.00 kg

Milk 0.36 kg 33 g 10.90

Typical Indian Family (Gupta family)• Let us calculate carbon emissions per month for

an Indian vegetarian family and a non-vegetarian family.

• Assumption: Family is of 6 people – 1 couple more than 60 years of age, one couple from 30-60 years of age, a boy and a girl under 30 years of age.

Energy requirementsPerson Age Body

WeightEnergy required (Kcal)

Male >60 70 2079

Female >60 65 1860

Male 30-60 75 2971

Female 30-60 60 2315

Male <30 50 2466

Female <30 45 1982

Total 13673Data complied from Indian Medical Research Council report on nutritional requirements in India. Energy required for rest is not taken into account. Work pattern is assumed to be moderate for all members of family. Energy requirements are on daily basis.

Carbon emissions for Gupta family• If all the energy was coming from wheat, Gupta

family will release 13673 X 0.151 = 2064 kg CO2per day

• However if Gupta family was non-vegetarian and all the energy was coming from chicken, it will release 13673 X 0.87 = 11895 kg CO2 per day.

veg Non-veg

Limitations• Diet is subjective even within vegetarian and non-

vegetarian domains. People fulfill their nutrition requirements from a variety of products which are not taken into account.

• Non-vegetarian humans also eat some vegetarian food like grains, vegetables etc. In the calculations shown, it is assumed that a non-vegetarian family will fulfill its requirements from meat alone.

• However, the figures are indicative of the difference in emission values.

Conclusions• It is shown through various calculations that non

vegetarian diet is inefficient in the matters of energy produced and emissions made.

• Same amount of energy output from beef can result in seventeen times more emissions when compared to wheat.

• Similarly other food products have been compared.

It is easier to take an individual step of quitting non-veg food rather than waiting for the world to develop technologies to mitigate environment damage.

References1. http://www.fao.org/newsroom/en/news/

2006/1000448/index.html

2. http://www.cleanmetrics.com/html/food_carbon_footprints.htm

3. A method to determine land requirements relating to food consumption patterns, Elsevier, 2002

4. Centraal bureau voor de statistiek (CBS), 1993. Statistisch jaarboek, 1993. CBS, Voorburg.

5. Lindeman, RL (1942). "The trophic-dynamic aspect of ecology”