Eat Like the Animals – What Nature Teaches Us about the Science of Healthy Eating is a fascinating book written by two brilliant scientists who are applying animal natural wisdom in human nutrition.
Although the authors tend to refer about themselves as “insect biologists”, they both have impressive careers and credentials. From their bios: “Professor Stephen Simpson AC is Academic Director of the Charles Perkins Centre, and a Professor in the School of Life and Environmental Sciences at the University of Sydney, and Executive Director of Obesity Australia.” and “David Raubenheimer joined the University in April 2013 as Leonard P Ullmann Chair in Nutritional Ecology.” You can read more about them in the links provided at the bottom of this post.
I have had the pleasure of attending lectures by Professor Simpson and sat down for a chat with him at one of Dietitians Australia’s conferences. His protein leverage hypothesis made an impression on me since I first heard him talk about it when I was a student.
Eat Like The Animals
This is a short and fascinating book, written in a language that is easy to understand by the general public. The introduction sets up the question answered in the rest of the book: how do animals know how to eat?
The book starts with the experiment that started it all, in which the authors observed locusts’ preference for protein. The plot thickens when the authors describe the discovery that locusts balance their food intake in order to reach a target protein amount. This means that locusts given a high carbohydrate diet overeat in order to reach their protein target, becoming “fat”. Conversely, locusts given a high protein diet do not meet their energy requirements and live shorter lives.
Besides protein, humans also have distinct appetites for other 4 important nutrients: carbohydrates, fats, sodium and calcium. The book also talks about the importance of fibre in controlling appetite and feeding the gut microbiome.
The authors’ observations led to the protein leverage hypothesis, which proposes that creatures have an optimal amount of protein intake and will overeat other macronutrients (fat and carbohydrate) if needed in order to reach that protein target. This is illustrated by the various experiments ran by the authors to give support to their hypothesis.
The authors highlight the fact that in many species, a high carbohydrate diet is associated with longevity and a high protein diet is associated with more offspring. They also point out that energy restriction, the restriction of certain nutrients such as the amino acid methionine and time restricted eating are associated with longevity.
The next part of the book talks about the use early use of fire and tools to change the food environment, followed by agriculture and food processing such as fermentation. Unfortunately, this has led to ultra-processed foods (more on this in a later post), which are at the core of the modern health crisis. This is exacerbated by the huge amounts of money spent on processed food marketing and the sad reality that much of current research is biased by industry funding.
The last section of the book emphasises the importance of protein for body function and the fact that the target amount of protein depends on biological factors and physical activity, and changes throughout life.
The protein targets provided in the book as a percentage of energy requirements are:
- Children and adolescents: 15%
- Young adults (18-30 years): 18-30%
- Pregnant or breastfeeding: 20%
- Mature adults (30s): 17%
- Middle age adults (40-65 years): 15%
- Older adults (more than 65 years): 20%
Other tips include:
- Avoid ultra-processed foods
- Focus on protein and fibre:
- Protein from varied animal and plant foods
- Fibre from leafy greens, non-starchy vegetables, fruits, seeds, whole grains and legumes
- Practise time-restricted eating for longevity
- Prioritise sleep and physical activity
The book closes with a glossary of terms, including proteins, amino acids, carbohydrates, sugars, starch, fibre, lipids, fatty acids, essential nutrients, and phytochemicals.
I also recommend listening to the short Eat Like The Animals podcast in which writer Charlotte Wood interviews the authors about their careers and the book.