A Doctor Tested Out 3 Trendy Diets — Here’s What She Learned

Dr. Seema Marwaha tries three diet trends to see if they offer any good lessons about healthy eating.

With hashtags like #dryJanuary and #NewYearNewYou creeping into my social media feed, it’s obvious that people are once again making resolutions to be healthier in 2018 — and it seems like the most common health resolutions involve weight loss or healthier eating.

As an internal medicine physician, I treat a wide variety of acute and chronic health conditions, and this is the time of year when a lot of my clients ask me for nutrition advice, and advice about certain fad diets.

As we all know, fad diets aren’t the key to healthy eating – long-term change comes from changes to lifestyle — but people are still drawn to them. And plenty of doctors, myself included, lack the training or resources to support individuals when they try to change part of their lifestyle. In medical school, I was taught that lifestyle modifications – things like being a healthy weight, managing stress, eating healthy and exercise – helped improve symptoms and prevent chronic disease. But I wasn’t taught how to help patients achieve these goals. And I found my own unhealthy eating habits – like my sweet tooth and love of greasy food – caused me to feel guilty when I tried to offer practical healthy eating tips. How could I give health advice that I couldn’t follow myself?

As many physicians do, I wrote off a lot of the blockbuster diets my patients try as ‘a fad’ or extreme (which many are). But I felt like I should be doing more. I decided the best way to understand the fad diets my patients were asking about was to try them myself.  I wanted to see if there was anything I could learn from them, but also understand the hype and the culture surrounding the fad, and challenge my own views about these diets in general. After trying Whole30, Low Carb High Fat and Intermittent Fasting for 30 days and consulting with nutrition experts, here is what I learned.

The diet: Whole30

The philosophy behind it: This rebrand of an ‘elimination’ diet — a short-term eating plan that eliminates foods that may be causing allergies or digestive reactions — became hugely popular in 2014. It is positioned as less about losing weight and more about figuring out which foods might be draining your energy, or feeding your stress levels.

It involves eliminating all forms of sugar, including natural sweeteners (like honey), alcohol, grains, legumes, dairy and soy for 30 days. The eliminated foods are re-introduced one at a time to determine which food might be causing you issues — with the idea that you would then kick that food or food group to the curb. The creators of this diet push for a very strict approach: any accidental consumption of an eliminated food means starting over from scratch. And making dessert-like foods out of approved ingredients (for example, pancakes out of bananas and almond meal) is strictly forbidden.

The upside: Elimination diets are ‘learning diets’ that can help you understand how certain foods affect your body — the elimination and staggered re-introduction of food groups can help pinpoint how particular foods make you feel and what to avoid.  This program is also a reminder that whenever you are making a lifestyle change that you hope to be long term, support is key. There is an extensive online community and multiple resources available to help people get through the 30 days.
Why The Stress Of Dieting Is Making Us MiserableWhy The Stress Of Dieting Is Making Us Miserable
The pitfalls: The program is designed to be temporary, and reinforces the idea that extreme changes are needed for you to eat healthier. Whenever you take extreme measures to counter a habit, it’s harder to make that change sustainable.

The diet: Low Carb High Fat (LCHF)

The philosophy behind it:  LCHF is a type of ketogenic diet – like Atkins or the “bacon diet.” But rather than just focusing on low-carb, it places a great emphasis on eating whole, unprocessed foods.

Rather than focus on just the number of calories you eat, the LCHF lifestyle is based on the premise that carbohydrates stimulate the production of insulin — the hormone your body uses to store fat. This diet replaces carb intake with fat intake. When you take in less carbs, you also (theoretically) access your existing fat stores for fuel. LCHF encourages you to cut out refined carbs (like bread and pasta), processed food and sugar. But it allows for liberal use of healthy fats like olive oil, avocado, coconut, butter, nuts and cheese.

The upside: Higher-fat foods taste good and add more flavour to meals, making the dietary changes easier to stick to. And unlike carb-rich meals, LCHF meals are not associated with a hunger-causing insulin crash afterwards. While LCHF has not been extensively studied yet, higher-fat Mediterranean diets have been linked to weight loss and lower rates of diabetes, heart disease and breast cancer.

The pitfalls: Extreme low carb diets sometimes make you feel guilty for eating an apple, and that feels weird. Not all carbs are bad – whole grains and many fruits and vegetables are part of a balanced diet for most people. 

The diet: Intermittent fasting (IF)

The philosophy behind it: IF involves alternating periods of fasting and eating. It’s more about when you eat rather than what you eat and is positioned as a change in your eating pattern, rather than a diet.

The simplest pattern it suggests to adopt is 16-8, where you eat for an 8-hour window during the day and fast for the remaining 16 hours. But there are more extreme fasting regimes where you fast for longer periods of time.

Proponents of IF say that fasting puts your body in a ‘mild stress state’ that builds resilience against disease. Just like LCHF, fasting can also drop your insulin levels, allowing you to (theoretically) use your fat stores for energy. Intermittent fasting might also just be an easier means to calorie restrict — by limiting the hours of the day when you can eat, you cut calories in the process.

The upside: Not eating after 8 p.m. is a good habit to get into for your overall health. Late-night snacking can disrupt your sleep patterns and contribute to acid reflux–type symptoms. Nighttime eating is usually a behavioural pattern and not mediated by hunger — so it’s often not worth the calories or side-effects.

The pitfalls: Fasting triggers the breakdown of both protein and fat, which might make some people experience more muscle breakdown than fat loss. Critics also say people might be prone to binge eating after their periods of fasting and that extreme fasting regimes can lead to malnourishment.

Remember: Any diet that promises “quick solutions” is likely preying on your insecurities rather than offering a path to healthier eating. And diets that are restrictive are not designed for sustainable healthy eating or a lifestyle change.

If you plan on making major changes to your diet, for whatever reason, consulting with your doctor is still a good idea. Making healthy, sustainable lifestyle changes is always something they will try their best to support.

Originally published January 2018; Updated January 2019.

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