Plant-Based Diets for Athletes and Sustainability

Buying local is supposed to be the easy good deed of grocery shopping. For beef, it barely moves anything. Dutch performance nutritionist Pieter Res ran the calculation himself: swap an imported steak, shipped by boat from Argentina, for one raised down the road, and the local cut still carries 99.3 percent of the original's environmental impact (10:13). The reason is unglamorous. Beef's footprint comes mostly from the land a cow needs over its life and the methane it produces, not from the fuel burned getting it to a plate.

Res has spent a long career feeding athletes rather than lecturing them about carbon. He has worked in professional cycling and football, including six seasons at the Dutch club Ajax Amsterdam, and with the Dutch Olympic team across sports such as speed skating (04:46). More recently he has tried to answer a narrower, harder question: can an athlete who needs huge amounts of energy and recovery eat in a way that is lighter on the planet without giving up performance? His answer, worked out across this conversation with host Danny Lennon, is yes, with details that matter more in practice than in theory.

Res frames sustainability using a concept from the Potsdam Institute called planetary boundaries, nine limits (things like freshwater use and land use) beyond which the planet's systems start to destabilize (06:03). Inside that framework, one food dominates. "The number one would be reduce the amount of beef that we eat," Res says. "It's just way bigger impact than anything else that you could do" (08:49). Everything else people worry about, buying local, choosing organic, avoiding plastic packaging, is a rounding error by comparison. Organic beef is actually worse than conventional beef on this measure, because organic farming is less land-efficient and beef is already a land-hungry way to feed people.

"Actually the worst thing you could have is organic beef, because beef is in itself a very inefficient way to feed people, and then organic is even less efficient." (Pieter Res, [10:36])

Plastic gets a similarly undeserved reputation. Res points to research showing that when a thin wrapper keeps food like cucumbers from spoiling, the greenhouse gas emissions avoided from reduced food waste can run about five times higher than the emissions from the plastic itself (11:29). None of this is an argument for packaging everything in plastic. It is an argument for paying attention to what is actually large (beef, mainly) rather than what is visible (a wrapper in a gym bag).

The Protein Problem, Reconsidered

The fear Res hears most from athletes, by a wide margin, is protein. The assumption, he says, is baked into how food is usually discussed: animal foods "have" protein, plant foods don't, really. The error is partly a labeling problem. Nutrition tables list protein per 100 grams of food, but the body runs on calories, not grams of food. When Res compares plant and animal foods on a per-calorie basis, the protein percentages turn out to be comparable (14:53). The more honest caveat is that a fully plant-based diet is less energy dense and higher in fiber, so hitting total calorie needs takes more food volume. But when an athlete meets that energy target, Res says, protein intake tends to fall into place on its own (15:54).

The second fear is about quality: that plant protein is somehow inferior once you clear the quantity hurdle. This idea traces partly to a widely cited 2010 study by researcher Jason Tang, which compared 20 grams of whey, casein, and soy protein and found soy produced a smaller rise in muscle protein synthesis, the process by which the body uses amino acids to build new muscle tissue (17:05). Subsequent research, including a series of studies from exercise physiologist Luc van Loon's lab in Maastricht, found that the gap closes once you give enough protein and combine plant sources.

"When you give enough protein, so around 30 grams or so for one meal, and you combine sources of plant-based proteins, then the ceiling of muscle protein synthesis is the same." (Pieter Res, [17:31])

Plant proteins don't lack amino acids, Res explains; the mix is just different from one source to the next, so one plant protein can be a little short on an amino acid that another is rich in. Combine sources and give the body roughly 30 grams in a sitting, or about 1.6 grams per kilogram of body weight across the day, and the difference from whey disappears (18:07).

What the Shift Actually Looks Like

The dietary-pattern question has rough numbers attached to it too. The Dutch Health Council has suggested at least 60 percent of protein coming from plants; the EAT-Lancet planetary health diet, a widely cited 2019 report on eating within environmental limits, works out to roughly 80 percent (13:04). Res treats 60/40, plant to animal, as a realistic floor for athletes rather than a ceiling, and notes that the current average among athletes he sees runs closer to 25 to 40 percent plant protein, meaning most have a long way to go even to reach the minimum (26:03).

Getting there raises a genuine logistics problem: plant-forward eating is bulkier and less calorie-dense, which is a real obstacle for an athlete who might need 5,000 kilocalories a day (21:26). Res's fixes are unglamorous. Smoothies pack calories without volume. On hard training days, he recommends low-fiber carbohydrates, white bread, white pasta, white rice, precisely the foods that usually get coded as unhealthy, because in that narrow context they're the easiest way to get enough fuel in (20:41).

Micronutrients get more nuance than alarm. Iron absorption from plants is less efficient in a single meal, but Res says the body adapts over time, absorbing more of it when stores run low, and population research doesn't show higher rates of deficiency in vegetarians or vegans (22:40). B12 is the one true non-negotiable: Res says anyone eating fully plant-based should supplement it (23:05). Omega-3s can come from algae instead of fish, sidestepping the fish question entirely. "There's no nutrient," he says, "that there's no solution for in another way" (23:55). One addition applies regardless of diet: Res recommends creatine supplementation for plant-based and omnivorous athletes alike, since dietary intake from meat and fish is suboptimal for performance purposes even for people who eat it (32:08).

None of this erases friction. Travel is the recurring practical barrier Res names: team meals, sponsor-driven menus, and international competition settings default to animal-centric plates, and sporting bodies themselves often set that default (18:34). His advice to nutritionists and organizations is less a policy than a habit: ask the athlete what they want and need, because the athletes making this shift tend to have already done the homework (29:47). On the question of how far an individual athlete needs to go, Res resists a universal number, preferring small, durable steps over the all-or-nothing switches he's watched athletes abandon after a month (13:29).

What ties the practical advice to the larger argument is Res's belief that athletes carry outsized social weight. He points to a UK project where athletes post plant-based recipes a few times a month, not to convert anyone, but to normalize the idea that elite performers can eat this way and thrive (27:10). It's a quieter theory of change than a dietary mandate: show, don't argue. Asked, at the end of the conversation, for one daily habit that improves life generally, Res didn't mention food at all. He said to talk to people outside your own bubble, because connection, he thinks, is both a personal good and a social one (33:34). For a conversation built on spreadsheets of emissions and amino acid ratios, it's a fittingly human place to land: the hardest part of changing a diet was never really the protein.