digest
Hi, I'm Dr Mike Evans, and today I'm talking about healthy eating. It's a huge topic. Eating seems simple, but it's actually pretty complex, so I thought I would just focus on what I'd say if you and I sat down in the clinic. I might start by wondering what you're shooting for: weight loss, less overeating, healthy eating, a longer, better life. Then, sticking with the big picture, I point out that eating is just one behavior in a healthy cascade. Exercising regularly leads to better stress management and sleep, which leads to better food decisions, to more energy, less chronic disease, and so on.
If it's weight loss you're after, that's easy conceptually: don't eat as much and move more. The problem is that it's not so easy keeping up this energy balance in the real world. In industrialized countries we are surrounded by a limitless supply of inexpensive, tasty, super-sized, high-calorie food. The other side of the energy balance equation, activity, has also changed. Our generation has a severe case of sitting disease: nightly TV, commutes, spectacular video games, moving sidewalks, and most of us are now sitting knowledge workers. Our culture pushes us toward the easy button instead of making our days harder. On the other side of the equation, I think it's important to remember that eating is grand. Food brings together families, builds communities, and gives us health.
Okay, so let's start with the question I most often get about eating: what's the best diet for losing weight? I'm not surprised people are confused. While you're watching this video, there is probably a pop-up window from the diet industry telling you about a diet, a detox, or a superfood, not to mention the Hollywood star who just started that diet. No research has shown convincingly that one commercial diet trumps all the rest. The only thing that predicted success in head-to-head trials was how well you stuck to whichever diet you picked. To reframe this: our society lurches from diet to diet looking for some magic formula, but it's not the formula so much as the pattern. Instead of obsessing about the exact composition of a diet, the science tells us to choose the one you like the best and can actually stick to. A Cochrane meta-analysis in 2015 looking at what boosted the success of commercial weight loss diets showed it wasn't less carbs or less fat; it was more structure and more in-person social support. Really, diets are just food rules that influence our pattern of eating, or what economists call a commitment device: what self-aware people do to improve their chances of controlling future irrational or impulsive behaviors. So instead of autopilot, you follow a food rule that nudges you toward certain eating decisions, mostly less overeating.
Each commercial diet has its own magic formula of what we call macronutrients: low carb, high protein, low fat, low sugar, and so on, and they typically have a story to go with it. So you can eat like a caveman, or use a scoring system, or buy prepackaged meals, or follow a famous doctor's take, or whatever. My two messages about macronutrients are: one, I think we spend too much time and energy focusing on them; and two, it's really more about quality than quantity. Low carb: carbs can be healthy in their complex form, fruits, veggies, legumes, whole grains, and not so healthy in their simple form, like free sugars and refined starches. Let's face it, carbs taste awesome, and our society tends to overeat them, so people who restrict their intake tend to lose weight. However, when we study relative weight loss outcomes, a 2014 systematic review by Dr Celeste and colleagues looked at weight and cardiovascular markers in at-risk people on low-carb diets followed for up to two years, and they found no difference compared to balanced weight loss diets.
So how about lowering sugar? If I had to pick one word to describe sugar in industrialized societies, it would be sneaky. So much sugar has worked its way into our diets. Many drinks have eight or more teaspoons of sugar, and the average American intake is approximately 20 teaspoons of sugar a day, more in teenagers and less in Canada. It's the obvious sweets, but it's also foods we think of as healthy: cereals, granola bars, and fruit juices. When high sugar contributes to excess calories, that is when we seem to get into trouble. One interesting caveat: when I diagnose patients with pre-diabetes, the first thing they do is drop sugar from their diet. However, when we look at the diabetes prevention trials, it was less about sugar restriction and more about the healthy cascade of being active half an hour a day, losing 5 to 7% of body weight, eating less saturated fat, and eating more fiber, which reduced the risk of progression to diabetes by 58%.
How about low fat? I think our story on fat has changed from all bad to more of a continuum. You have trans fat, found in fried fast food and many packaged baked goods: not so good, and we're reducing these. We have saturated fats, mostly in dairy, red meat, and plant oils like coconut or palm: these seem not so good in excess but okay in moderation. Then we have monounsaturated fats, or MUFAs. The Mediterranean diet, which I'll discuss in a second, is pretty high in MUFAs, so avocados, nuts, seeds, olive oil, and dark chocolate, and these show health benefits. Finally, we have PUFAs. These are the longer-chain fats found in oily fish. Early trials showed some reduction in cardiac events; more recent trials have not been so enthusiastic, though meta-analyses still show some small benefit and no harm. So the suggestion is at least two servings a week. People seem to do better when they replace saturated fats with MUFA and PUFA fats.
What about high-protein diets? Again, it's more quality than quantity. Protein can come in different packages with different health effects. Compare a high-salt ham steak with a salmon steak, lentils, or a handful of almonds. Most data point to the fact that if you eat healthy protein, white meat, nuts, beans, fish, you do better, especially if it is spread throughout the day, and perhaps most importantly at breakfast. There are also some diets showing good results in people with disease. The DASH diet drops high blood pressure by 5 to 11 mm of mercury, and a low glycemic index diet lowers A1C, the measurement of blood sugar over time, in people with diabetes by 0.5 percentage points. Many of our patients have high cholesterol, and Dr David Jenkins and his colleagues here at the University of Toronto have shown they can reduce cholesterol by 35% with the portfolio diet. The data for vegetarianism has largely come from cohort studies, and now some randomized trials show that people do better. It's hard not to conclude that a diet rich in plant-based, unprocessed foods is a smart diet. Of course, many people make the excellent point that the burden on our planet is less with a vegetarian, vegan, or local diet.
One way to think about all this is to reflect on Brazil's new dietary guidelines. Here they shifted from focusing on the perfect macronutrient mix toward more appreciation of food. Stepping back a bit to see that we're buying more ultra-processed and packaged foods that can be eaten anywhere, there may be an opportunity for healthier eating and better relationships by encouraging meals with your family and friends.
Okay, if there's no magic formula, is there a diet that actually does work? I think the answer is yes. The diet is more about culture and small behaviors, a diet not focused on weight loss but on healthy outcomes like less cancer, less heart disease, less dementia, and a longer life. The diet with the most robust evidence is the Mediterranean diet. Instead of food rules or absolutes, this is more about moderation: less meat, more veggies, fruit for dessert. I think shopping at the market, or at least at the outer aisles of a grocery store rather than the processed foods for sale in the inner aisles. It's called the Mediterranean diet, but really it's more of a lifestyle, a region that traditionally includes lots of physical activity, regular meals, and good social support.
Let's continue the shift from diets to healthy behaviors that affect our eating by looking at the National Weight Control Registry, the NWCR. It administers an annual questionnaire to more than 10,000 people, more women than men, who have lost quite a bit of weight and kept it off for more than a year. Not surprisingly, 98% said they modified their food intake in some way, and 94% increased their activity levels. But there wasn't one formula. Most restricted some foods, some counted calories, others ate all foods but limited their quantities. 78% ate breakfast every day. The majority watched less than 10 hours of TV and ate out just three times a week, and these people generally exceeded the prescribed half hour a day of activity, averaging an hour a day, mostly walking. Nearly all registry members indicated that weight loss led to improvements in their energy level, physical mobility, general mood, self-confidence, and physical health. A feedback loop seemed important. Losing weight is one thing, but the trickier part, at least for about 80% of us, is keeping it off. Weighing yourself and using this as a small nudge in your daily food decisions is one example: 75% of NWCR subjects weigh themselves weekly and 36% daily. They looked at this more closely in the STOP Regain trial, where daily self-weighing was associated with a decreased risk of regaining 2.3 kg, or 5 lbs, on average. Another feedback nudge is a food diary, even just for a week, and that's easier now with apps. Patients find this so simple they don't do it, but seeing what you have eaten can actually double your weight loss. I think awareness is undersold. It might be what you're eating or weighing, but it's also about knowing that life is messy, and to enjoy it we need some flexibility, or the sense that you simply feel better when you eat better.
That's why I like the idea of starting with small changes, or as I call them, tweaks. Maybe switch something you do a lot. For example, with eating breakfast, snacking, or drinking, you could switch your average cereal for some oatmeal or shredded wheat, or a handful of almonds instead of a bag of chips, or switch three of your colored drinks a day to water. I know this doesn't sound too sexy, but the Dr Mike switcher diet might actually chip off a pound a week, or better yet, make you feel better. Another angle is adding instead of subtracting. Dr Sheri Pagoto and colleagues randomized metabolically at-risk individuals to either a multifaceted American Heart Association diet or simpler advice of just increasing fiber to 30 grams throughout the day. Both groups lost weight, the high-fiber group slightly more, and both improved cardiovascular markers. I like this idea of pushing healthier food rather than just restricting or fencing off other foods. Other data show satiety, the feeling of being full, is not just about calories; calories that come from protein and fiber can actually make us feel more full.
Another angle is social support, which can help our eating behaviors. In one study, people were either going it alone or had three or more friends or family members supporting them, and maintaining weight loss at 10 months jumped from 24 to 66%. On the subject of support, having a dietitian, even if just online, helps. They're like a Genius Bar for your eating. Activity is also interesting in the context of eating. Research shows that people who are active, even when they have obesity, live longer than skinny sedentary people. Some tell me they are active but have been unsuccessful at weight loss. I shrug my shoulders and say, actually, you have been successful, you're active. It's easier to drop calories through diet, but I think it's important to know that research shows people who exercise have more success at maintaining their weight.
My final two points about healthy eating focus on the long-term view and attitude. Restrictive diets have proven hard to sustain, so many are now turning from the individual to what surrounds the individual, changing our eating environment to make it easier to make the right choice day after day. We call this redesigned choice architecture, and it involves two types of what I call awareness. The first is knowing that our world is full of triggers toward unhealthier overeating: convenient, shiny foods at the counter, super-sizing, marketing. As Dr Brian Wansink points out, most of us don't overeat because we're hungry. The second is awareness of what nudges you personally. We are creatures of habit. We do the same thing every week, and each of us has cues: certain foods, pastries at the coffee counter, a time of day, a predictable stressor. As Wansink says, the opportunity here is to re-engineer small behaviors that move you from mindless overeating to mindless better eating. Maybe it's redesigning your kitchen. When you leave cookies on the counter, they are much more likely to be eaten, but the same is true for fruits and veggies. Smaller plates and glasses, fewer super-sized containers, and not eating from the bag are simple nudges to reduce mindless eating. Redesign takes some self-knowledge. Are you a nighttime nibbler or an emotional eater? I'm a grazer; I'll eat whatever is there, so my change is at the grocery store. I know it's pathetic. I should cut fruit myself, but mindless healthy eating happens for me when I buy pre-cut fruit. Just like I might tell a smoker not to have cigarettes in the house, I also don't buy super-sour gummy candies, because I can't stop eating those things.
My final behavior is more of an attitude: 80/20. If you're making the healthier choice 80% of the time and your 20% is not too high in calories, you should be thrilled. Having a piece of dark chocolate, a good meal out, or pie is fine. We're in this for the long term, so I'm not looking for perfection; I'm looking for consistency.
In the end, I hope I've got you to think a bit differently about how you eat: instead of investing in a single diet, a portfolio of behaviors; small tweaks over big changes; single-ingredient foods over multi-ingredient and processed foods; dinner at home; self-awareness; depending less on constant willpower and more on tweaking your week to make mindless healthy eating more likely. My final point is more about health at every size. I get that people want weight loss, and obesity is a risk factor for disease, but honestly, if my patients can work with their factory settings to be more mindful of their eating, move a bit more, practice more self-love, and start thinking more about what's healthy to eat rather than what not to eat, I'd be happy. So maybe now is the time to start your very own better-life experiment. Thanks for listening.