The Game Changers – Should You Change Your Game?

Dr Warren Bradley PhD, Lauren Halsey, Tim Clarke and Paul Harter
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We are: one omnivorous doctor of nutrition and human physiology; one omnivorous certified nutritionist (and former partner at a major international law firm); one omnivorous certified nutritionist (and former GB rower); and one vegan fitness coach. 

We thoroughly enjoyed watching the Netflix documentary “The Game Changers”. We have the education and expertise necessary to watch each scene, strip the wheat from the chaff, and separate truth from fiction. We have the skills to read the research and make judgements about its validity. We have the experience to spot omissions in the narrative that are critical to assessing the accuracy of the bold statements that are made. Even if you do not have this background, you can still enjoy the documentary, but we suggest you consult a skilled, evidence-based nutritionist or dietitian before changing your game.

Our bottom line: A plant-based diet is a great way to promote health and performance.

A plant-based diet supplemented by moderate, but adequate, amounts of high-quality animal-based proteins and fats – probably even better. 

We are not anti-vegan. We deeply respect people who make moral judgments about killing and eating animals or about the environmental impact of animal husbandry. We are anti-hysteria, anti-propaganda and anti-falsehood. We work with vegans to help them optimise their health and performance taking into account the restrictions on their diet. We believe veganism is deeply personal. Veganism can never be proven by science.  It must be respected, but never proselytised.


Many people have already critiqued The Game Changers, alleging inaccuracies and scientific weaknesses and omissions in the very bold assertions made in the documentary. 

Examples include: (i) the Roman gladiators were vegans; (ii) vegan men have stronger and more frequent erections than meat-eating men; and (iii) Nate Diaz beat Conor McGregor because Nate is a vegan. All false (at least far more likely than not). The film does engage in deliberate deception to fuel its narrative. The burrito scene is an example. They compare blood test results after eating a bean burrito and a burrito loaded with meat and cheese. The meat burrito, containing at least double the fat content of its vegan counterpart, caused post-prandial lipemia (fatty acids circulating in the bloodstream after consuming a meal containing fats) to a much larger degree. Due to this manipulation, significantly more fats entered the bloodstream resulting in a cloudy appearance once centrifuged and separated. Lipemia results from eating fat, not meat. It’s completely normal and it goes away. And fat is an essential part of the human diet. Had the vegan burrito been full of cashews, vegan cheese or other plant-based fats, the result would have been the same. The film also uses lab coat bias as a tool to manipulate the audience. If a doctor uses big words to make a point, people unquestionably assume the doctor is right. In this case, he’s not. But he does make a lot of money selling vegan food or books on veganism.

We start with the good in The Game Changers: eating fresh fruit, vegetables, beans, legumes and whole grains is really, really good for you.

They are a great dietary source of many of the essential vitamins and minerals that your body needs to perform optimally. They are the best dietary source of fibre to support gut health. They are a great dietary source of polyphenols, and other antioxidants and anti-inflammatories, to help keep you young and free of illness. They are full of carbohydrates to provide energy and fuel performance. They are a critically important part of the diet of anyone seeking to optimise health and maximise performance. Plant-based nutrition is good.

Removing all animal-based nutrition for most people may be less good.

Let's take an educated look at three key nutrition points: protein, micronutrients and dairy and reveal the evidence that Game Changers leaves out of their narrative.

Adequate Protein

Game Changers points out that athletes need carbohydrates, not protein, for energy. That is correct. But, everyone needs protein to repair and maintain strength and lean muscle mass (as well as to optimise hormone production, including sex hormones). Game Changers then tells us people don’t need animal sources of protein, and to prove the point, they parade vegan strength and endurance athletes, claiming that they get more than enough protein from plants. The truth: athletes can easily get sufficient protein from plants. Office workers often cannot. It’s simple arithmetic. Allow us to explain:

Currently, scientists generally concur that people optimally need 1.2 to 2.0 grams of protein per kilogram of bodyweight per day. At 2.0 grams, a person weighing 80 kilos needs 160 grams of protein per day. An 80-kg endurance athlete could be expected to burn 6,000 kcal per day (and therefore need to eat around 6,000 kcal per day to maintain bodyweight -- neither gain nor lose weight). A sedentary 80-kg office worker could be expected to burn 2,000 kcal per day (and therefore need to eat 2,000 kcal per day to maintain bodyweight).


Let’s look at plant-based sources of protein:



Protein per 100 grams

Kcal per 100 g

Protein per 100 kcal


9.0 g

116 kcal

7.8 g


2.8 g

34  kcal

8.2 g

Kidney Beans

14 g

220 kcal

6.4 g


10.6 g

94 kcal

11.3 g


And grilled chicken breast:


Chicken breast

31 g

165 kcal



So, to consume 160 grams of protein from just one of the above sources:



Grams of Food for 160 g Protein

Kcals for 160 g Protein


1,777 g

2,061 kcal


5,714  g

1,943 kcal

Kidney Beans

1,142 g

3,172 kcal


1,509 g

1,418 kcal

Chicken Breast

516  g

851  kcal


You’re a vegan athlete eating 6,000 calories per day. It’s pretty easy to get adequate protein from plants. You’re an office worker eating 2,000 calories per day – it’s considerably more difficult, unless you’re prepared to eat 5.7 kilograms of broccoli or 1.7 kilograms of lentils per day (or else increase your daily calorie consumption, and gain a lot of weight). We can quibble about whether the optimal protein consumption is 1.2 grams or 2.0 grams per kilogram bodyweight. We can quibble about whether the athlete actually burns 6,000 kcal today or somewhat less than that. But the point we make is clearly demonstrated using any reasonable, realistic set of variables.

Adequate Vitamins and Minerals

Despite numerous health benefits associated with plant-based foods, eating just plants at the exclusion of whole food groups such as meat and dairy, can quite rapidly result in nutritional deficiencies.1 Hundreds of studies have illustrated the negative impact on the body associated with nutrient deficiencies,2 many of which have been conducted with vegetarians and vegans. Imagine trying to ride your bicycle without regularly oiling the chain. It would still work (for a while) but it would begin to show signs of wear and eventually grind to a halt. 

Nutrients such as Vitamin B12 and creatine are found almost exclusively in meat and dairy, whilst others such as Iron and Calcium (to some extent) are found in small quantities in plants, but are significantly less bioavailable (less able to be absorbed by the body). Some grains, legumes, nuts and seeds also contain compounds called phytates that block nutrient absorption (such as Iron), meaning more nutrients need to be consumed for adequate absorption. This may be tricky when foods contain low concentrations of these nutrients and have a lower bioavailability in the first place. 

Let’s look specifically at Vitamin B12, Iron and Calcium.

Vitamin B12 is involved in the metabolism of every single cell in the body. It is probably the most important deficiency resulting from plant-based diets.3 Vitamin B12 is found in wild fish, eggs, grass-fed beef and dairy products. Although it is found in an alternative form called cobamides in sea vegetables, algae and seaweeds, the bioavailability from these sources is particularly poor. So, regardless of what you choose to eat within a plant-based diet, this nutrient will rarely reach optimal levels without supplementation. 

Iron is required for oxygen transportation in the bloodstream (haemoglobin) to the cells. Deficiency results in anaemia, fatigue, low sex drive and becoming short of breath as your body attempts to increase oxygen delivery to the cells. There are two different forms of iron: heme and non-heme. Heme, found only in meat, is highly bioavailable,4 whereas non-heme, found in dairy, eggs and plant foods, is much less bioavailable. Dark leafy greens, nuts, seeds and legumes contain relatively high amounts of non-heme iron, but legumes also contain phytates which block the absorption of nutrients such as iron. So, go easy on the beans if you want to absorb your iron!

Calcium, found predominantly in dairy, is essential for the development and maintenance of the skeleton, and also for heart, muscle and nerve function. Deficiencies are associated with numerous osteo (bone) issues such as osteoporosis or ‘brittle bones’ resulting from very low bone mineral density.5 In a study of 1475 adults, vegans had significantly lower calcium intakes than vegetarians and omnivores, and fell short of national recommendations. Findings from a meta-analysis of several studies on Calcium also predict a higher risk of bone fractures in vegans. Although found in dark leafy greens and fortified soy products, adequate daily consumption of these foods is required to avoid deficiency, and therefore supplementation may be necessary.6


Game Changers vilifies dairy. However, they ignore the many studies that show an association between dairy consumption and positive health outcomes, including improved blood lipid profiles and a reduction of the risk of cardiovascular disease7 and improved insulin resistance and a reduction of the risk of type II diabetes.8

Yes, some people are lactose intolerant. Most people are not. Though our hunter/gatherer ancestors did not consume milk products after weaning, in the 12,000 years since the beginning of the agricultural revolution most humans have evolved to be able to digest dairy and include dairy as a healthful part of their diet. Many indigenous populations, such as the Masai, consume large amounts of dairy, yet live largely free of the age-related diseases that plague the Western world.

Game Changers is the next instalment in the crusade to get people to stop eating animal products, written by people who believe that the ends justify the means. While their goals may be noble, their methods are not. There is a lot to be said for eating a predominantly plant-based diet, whether or not you also include some animal products in your diet. Healthy veganism takes discipline and hard work. It’s a personal choice each of us can make for ourselves. 

Veganism is an ethos for living, not a product to be bought and sold. It goes beyond what you eat and includes all aspects of the human relationship with animals and the environment. Vegans have no need for Game Changer’s sensationalism to justify their moral choices. And conversely, that very same sensationalism fuels reactive anti-veganism, which is equally unhelpful. If you are confused or need help deciding what’s best for you, consider consulting an expert who knows the science and is free of personal agendas.


1 Derbyshire (2018); Larpin et al. (2019); Sanders (1999)

2 Larpin et al. (2019)

3 Pawlak (2013)

4 Valenzuela et al. (2009)

5 Lanham-New (2008); Smith (2006)

6 Larpin et al. (2019)

7 Warensjo et al. (2009); Elwood et al. (2004); Bonthius et al (2010).

8 Mozaffarian et al. (2010)

  1. Shanna Colburn says:

    This article was extremely helpful. Thank you for clarifying the skepticism in the “Game Changers”. I now have both sides of the story and a better base for my dietary plan.

  2. MelissaTor says:

    There are many arguments about which diet is best for you. Nevertheless, health and wellness communities agree that diets emphasizing fresh, whole ingredients and minimizing processed foods are superior for overall wellness plant based diet and mental health. The whole-foods, plant-based diet does just that. It focuses on minimally processed foods, specifically plants, and is effective at stimulating weight loss and improving health. This article reviews everything you need to know about the whole-foods, plant-based diet, including its potential health benefits, foods to eat and a sample meal plan.

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