Having attempted to educate several friends, partners and relatives on how they can improve their diets over the past few years, it is becoming to clear to me that this is an area that confuses and enrages many practically-minded people. I remember seeing somewhere that “the best workout program is the one you’ll actually do”, and the same is true of a diet. Unless you’re the kind of person who will count calories and keep an excel spreadsheet in your phone, or who is willing to figure it out once and then eat the same thing every day for months (hi!), all you probably want is simple-to-follow rules of thumb that will have you roughly on track. With that in mind, I present to you… healthy eating for idiots. If you don’t care about the rationale and just want the instructions, head straight to the dot points at the end.
An acceptable diet satisfies the following criteria: it provides you with enough vitamins and minerals (micronutrients) and appropriate ratios of fats, carbohydrates and protein (macronutrients), it doesn’t make or keep you overweight (or underweight), and it is comprised of foods you’re willing to eat. The first requirement is satisfied by eating enough whole foods (vegetables, fruits, legumes, nuts and seeds, meat if that’s your thing), the second by eating roughly the right ratios of them, and the third by eating mostly things that are low insulin response / low caloric density (which I will explain shortly). The fourth requirement will dictate how you meet the other three, since most people can’t subsist on lentils and avocados.
First, let me explain caloric density and insulin response, since these to a large degree dictate what’s good for you and what isn’t, and understanding them will mean you can figure some things out for yourself. Caloric density is, as you might expect, the number of calories a given type of food contains by weight – this is determined by whether it’s mostly fat, protein, or carbohydrate, and then by how much of it is actually digestable (ie how much fiber it contains). Things that contain no fiber at all, like refined sugar or oils, have the maximum caloric density possible. Things with high fat content have higher caloric density than things that are mostly protein or carbohydrate, since fats contain more than twice as many calories per gram (9 vs 4). So for example 100g of oil (pure fat) contains 900 calories (three meals’ worth), and 100g of broccoli (a lot of fiber and a small about of carbohydrate) only contains 34 (barely a snack). If you want to get a sense of this for yourself, look at the nutritional information labels of different stuff in your kitchen: broadly speaking, any solid food with fewer than 100 calories per 100g is fine, eat as much as you want. Beyond that point, the higher the number of calories per 100g, the less of that type of food you should eat.
One of the reasons this matters is that caloric density to some extent determines how your body responds to a food. You’ve probably heard people recommend “complex carbohydrates” over “simple carbohydrates”; this is related to that. Things that are digested quickly cause sudden spikes in your blood sugar and / or your insulin levels. This is generally bad, unless you are about to do intense exercise or are in the middle of running a marathon. If you spike your insulin levels regularly over a long period of time (in the absence of intense exercise), for example by eating junk food or drinking soft drink on a daily basis, your body will react less and less to insulin, much like how regular consumers develop a tolerance to coffee or alcohol.
Insulin regulates your appetite, as well as how efficiently your body can use fats and carbohydrates from food for energy. As you become resistant to insulin, these mechanisms get messed up, and your appetite increases, meaning you need to eat greater amounts of calorie-dense foods to feel full, and your body’s ability to use the energy from those foods is obstructed, meaning that you gain weight. The more you eat and the more weight you gain, the more insulin resistant you become, creating a vicious cycle which, if you are unlucky, ends in obesity and / or type two diabetes. The details are both complicated and controversial, but this is, in very brief and simplified form, part of what’s wrong with the standard western diet. It’s not that we eat “too much” – it’s what we eat too much of. You could eat kilos of brocoli per day and I promise, this would not happen to you. Which brings me to my actual advice.
1) You need to eat vegetables. Not only because they contain micronutrients and fiber, which you need, but also because in general, you can eat large volumes of them without spiking your insulin. This means you can eat multiple large meals a day without making yourself insulin resistant. It is very hard to do this if your meals don’t contain vegetables. Man should not live on pizza alone.
Not all vegetables are created equal; some have much higher nutrient content and lower caloric density than others. Potatoes are basically worthless, and should really be considered an honourary junk food. For the purposes of healthy eating, they do not count as a vegetable. Sweet potato, on the other hand, is much lower caloric density and actually contains useful vitamins. This is generally true of things that are yellow or orange – carrots, pumpkin, sweet potato, capsicum are all great, eat a lot of them. Vegetables that are not worth your time are detailed here. Broccoli and cauliflower are good, as are, of course, leafy greens. Pick whatever non-worthless vegetables you consider palatable, and go nuts.
2) Cut the crap. This commandment is formulated differently in different dumb weight loss fad diets, but it’s really pretty straight forward. Obviously fast food and soft drinks are terrible. More generally, anything that is high caloric density and isn’t in exactly the same form as it would fall off a tree or come out of the ground is bad for you. Nuts and fruits are okay, but fruit juice is not – it usually has four times as much sugar and a fraction of the vitamin content of actual fruit. The stuff you buy off the shelf in the supermarket has the same nutritional content as cordial – i.e., nothing beyond a bit of added vitamin C. Ditto dried fruit – it’s okay in very small amounts if mixed in with healthier things (for example in muesli), but it is not a good thing to eat on its own. If you want to get technical, table 4 in this paper contains a list of common foods and their insulin response per gram in the third column from the right. The lower the score, the more of that food you can eat.
One not-unreasonable rule of thumb is “don’t eat anything white”. This possibly goes a little far, since it also excludes a few things you actually should eat (cauliflower, barley), but there are a few white things you should definitely restrict or cut completely. Potatoes, as mentioned previously, and much more critically for the average western-diet consumer: bread. White bread is actually the index against which the insulin response of other foods is measured – it provides the high water mark. Several slices of white bread is about the equivalent of a can of coke both in terms of micronutrient content (i.e. none) and what it does to your blood sugar. I’m not kidding. Brown bread is barely any better, although wholegrain is a slight improvement, and heavy German-style bread like pumpernickle is okay. If you are going to eat bread at all, eat it with low caloric density things; as part of a full breakfast with spinach and mushrooms the insulin spiking effect would be dulled somewhat, but toast and jam for breakfast every day is about as good for you as a mars bar. This goes for anything made by a baker, really; it’s junk food. A couple of times a week is fine, but bread shouldn’t be a staple of your diet any more than cake should.
So that’s carbohydrates; cut things that are high in sugar (especially drinks), or mostly carbohydrate while low in fibre and micronutrients (bread and potatoes). What about fats? My suspicion is that when most people cut potatoes, they cut a lot of fat from their diets as well, since once way or another we often have potatoes doused in oil. Unless you’re eating a lot of fatty meat, or you’re a vegetarian living on macaroni and cheese (not that I would’ve known anything about that as a teenager), once you cut out fried potatoes and fast food, you’re probably okay with fats. Avocados and nuts are probably preferable to animal fats, but in general if you’re eating enough vegetables and you’re not gorging yourself on low-grade meat (if you are, stop), I think it’s hard to get this too wrong. And take note: foods that are advertised as “low fat” are often high in sugar. They’re both bad. As an aside, the whole obsession with low fat dairy is ridiculous – unless you’re drinking litres of milk a day, the fat content is inconsequential. Don’t go eating double cream from the tub with a spoon and things will probably be okay.
Lastly, protein, since it would seem odd to omit it. If you eat meat every day, you are probably getting more than enough. If you’re vegetarian or vegan you may or may not be, depending on how much tofu and dairy you eat. It’s actually pretty hard unless you eat a lot of soy products or lentils. Most recommendations seem to be roughly 1g per kilo for anybody who isn’t doing seriously strength training. For a 70kg meat eater, 300g of meat a day will do them, and anything else would be a bonus. For a 70kg vegetarian, however, according to google, 70g of protein would require either three cups of lentils, 12 eggs, 2 litres of milk, or almost a kilo of tofu. I guess 500g of tofu and a cup and a half of lentils is doable in a day, but eggs are clearly not the answer to anybody’s problems. In general, if you’re happy with your weight and you’re not doing any strength-based exercise, you probably don’t need to worry about it. If you are worried about it, there are plenty of vegetarian and vegan protein supplements. Just don’t buy one that’s 30% sugar.
I said I would make this simple and it seems to have dragged on, so here is a summary:
- More vegetables! Potatoes don’t count. Green things and orange things tend to be the best. Your lunch and dinner should ideally contain at least as much vegetable matter, by volume, as any other kind of food.
- More whole foods! Legumes, nuts, fruits, mushrooms, whatever, as long as it’s still basically in the form it came out of the field in. Rice isn’t great, barley and lentils are better.
- Pretty much any drink that isn’t water, milk, tea or coffee should be limited to occasional consumption – soft drink, fruit juice, “sports” drinks (aka sugar-water), beer, etc. Look at the nutritional information label – if it has more than 5g sugar per 100ml (eg 2-3 teaspoons per cup), it’s bad for you.
- Nothing made out of ground wheat / rice / corn is good for you. Anything made by a baker should be considered junk food – this includes bread. Pasta and noodles are okay if they’re had with vegetables, but they’re not great otherwise.
- You don’t need to worry about fat as much as most people seem to, but large quantities of fatty meat or high-fat dairy (cheese, cream) aren’t great, nor is a lot of coconut cream. Eat as much avocado as you want, though.
So that’s it. It’s not nearly as complicated as people make it. If all you’re trying to do is avoid a heart attack in your sixties, just follow the suggestions above. If you’re trying to lose weight, be especially strict about sugars / non-vegetable carbs and start walking everywhere you can. And if it’s still too hard and you really, desperately just want to eat whatever the hell you like, take up long distance running and find a good multivitamin supplement.