It was at that moment Suzy decided to do everything she could to inspire others to cut back on eating animal products. The result is her book, OMD: The Simple, Plant-Based Program to Save Your Health, Save Your Waistline, and Save the Planet.

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"OMD" stands for "one meal a day". Rather than encouraging people to cut all animal products for good – which Suzy admits can be challenging – she's suggesting we substitute one "regular" meal each day for a plant-based one.

Making that change will have a huge effect on people's health, she says, adding that those who eat less red meat and more vegetables have "lower blood pressure … less thickening of the blood vessel walls and less hardening of the arteries" than those with a meat-heavy diet.

Since adopting a fully plant-based lifestyle, Suzy says James has shed 13 kilograms and neither has suffered a single cold, flu or stomach upset. "I'm in the best shape of my life," she adds.

Meanwhile, the benefits for the planet are equally impressive. In her book, Suzy writes that, per calorie, the production of beef generates six times more greenhouse gases than that of chicken, and up to 45 times more than for soy products. "Every time you eat plant-based, you cut your carbon and water footprints by a third."

Better yet, OMD is easy to do. For instance, Suzy suggests substituting the cows' milk on your breakfast cereal for soy or almond milk, or chowing down on a bean burrito instead of beef at lunch. She also recommends easing into the process, writing, "Start by cutting out the one meal where you don't even really 'need' that meat."

Dietitian Kathryn Hawkins loves the idea of OMD as a "great way" to give the body a break from large amounts of protein while filling up on good-quality fibre and antioxidants. However, she's concerned that those who choose to adopt this diet fulltime may fall short on protein, iron, zinc and vitamin B12, all of which are readily available in animal products. Consequently, she says, adopters may require monitoring and supplements.

Suzy agrees that supplements such as vitamin B12 may be needed by full-time followers of the regimen. But she believes concerns about protein are unfounded, saying we eat almost twice as much as we need. Besides, she writes, if you add up the protein in beans, grains and vegies, "it's more than enough for you".

OMD is about substituting one meal a day for a whole-food, plant-based one. But Suzy hopes that, as people begin to "feel better", they'll be eager to embrace such a regimen even more, thus making a bigger difference to both their own health, and that of the planet.