Moughan is gathering research for a book to be published next year, which will explain the science behind weight loss and nutrient supply from foods in plain language. His aim is to free people from dieting hell and improve their health. Nutrition expert and endocrinologist Dr Robyn Toomath after 40 demoralising years of treating obesity in highly motivated clients concluded in her 2016 book Fat Science that yo-yo dieting ultimately just makes people fatter.

This is sadly true, but its not hopeless, says Moughan. What people need to do is forget about how much they weigh and instead concentrate on changing their body composition turning fat into muscle. That means consuming a higher proportion of protein in the diet and getting more exercise. You will feel fuller and more satisfied rather than deprived. The more muscle and lean body mass you have, the more you can eat without putting on weight. Muscle cells use energy provided you actually use them and are constantly being renewed, which uses even more energy, unlike fat cells, which are akin to inert storage units.

He is quick to add: I am certainly not recommending that you follow an Atkins-type diet of unlimited bacon and eggs to the exclusion of fruits, vegetables and grains. Just eat a higher proportion of good-quality protein, get lots of fibre, and do the right type of exercise regularly. Even half an hour of dedicated brisk walking three times a week is good. If you do that, you will probably automatically consume fewer fats, oils and refined [highly processed] carbohydrates. And dont worry if you weigh more in the short term. Muscle, on a per calorie basis, weighs more than fat.

Balance is important. We need fruits and vegetables to supply some of our vitamins [like vitamin C, E and K], fibre, carbohydrates and other components.

Counter-intuitively, vegetarian and vegan diets can be more calorific because you have to eat a much greater quantity to get the same amount of protein, and there is a tendency to consume more fats, oils and refined carbohydrates. This is especially true when aiming for higher protein intakes. Which is not to say that many vegetarians are not perfectly healthy, slim and fit, or that many meat eaters are not unhealthy and overweight.

However, it is not animal protein that has driven the obesity epidemic, according to Teresa Davis, professor of paediatrics-nutrition at Baylor College of Medicine in Houston. While giving a public lecture in Palmerston North during a 2018 visit, she reported that in the US, average daily calorie intake by adults increased from 2060 calories in 1970 to 2630 in 2008 a whopping 570 extra calories. Davis showed the extra calories have come mainly from oils, fats, flours and cereals, and interestingly not very much at all from extra sugar, which was already quite high in 1970.

Read more: The risks of removing entire food groups from your diet |

She said in Western countries, people derive two-thirds of their protein from animal sources; in developing countries it is the other way around they get two-thirds from plant sources. It is projected that by 2050 the demand for animal proteins from the developing world will likely double, as their middle classes grow.

Lisa Te Morenga, senior lecturer in Mori health and nutrition at Victoria University, says with the increasing use of social media in the last 10 years, there has been a rise in conflicting messages about what we should or shouldnt be eating. First it was high-fat diets, then paleo and now vegan and plant-based diets are dominating headlines. I worry about the impact of all this conflicting messaging on New Zealanders diets, and how this might affect population health long-term. Unfortunately, we have little idea of what New Zealanders are eating right now as we havent had a national adult nutrition survey since 2008/2009, and the last childrens survey was in 2002. Given that the Global Burden of Disease project cites poor nutrition as the number one risk factor for early death, this really is an urgent priority. We need to monitor the effectiveness of food and nutrition policy and research in New Zealand.

McNabb has caveats about changing diets. Our digestive systems have not evolved much in the last few thousand years. A switch to getting all your proteins from plants is challenging; it is quite a different nutritional scenario.

Riddet Institute postdoctoral researcher Lakshmi Dave, a vegetarian by upbringing and now by choice, says her biggest concern with modern diets is ultra-processed foods and drinks, especially sugary ones, and processed red meats. Dave is a strong advocate of dairy foods and having lots of in-season fruits and vegetables on the plate, including those that are available but for whatever reason are not commonly cooked and eaten. Neglected or minor crops New Zealand native puha, for instance are important for sustainable and climate-resilient food systems as they help diversify food production. They are also nutritionally significant since they tend to be rich in key micronutrients. Unfortunately, these crops tend to be marginalised due to inadequate research, unsupportive agricultural policies, and modern dietary patterns that rely on a very limited number of major crops, says Dave.

Newbie vegetarians and vegans must be careful with things like pulses and legumes, such as red beans, which must be properly soaked, germinated and/or pressure-cooked to reduce the levels of anti-nutrients that can compromise their nutritional value and digestibility. Frozen vegetables and cans of cooked chickpeas, red beans, etc, in water dont count as ultra-processed in my book, but you should aim to have a dietary pattern in which meals prepared from minimally processed ingredients are the mainstay. And dont starve your gut microbiota get enough fibre!

More here:
Is the vilification of NZ's meat and dairy justified? - Noted