Here's What Our Nutritionist Thinks About 2018's Hottest Diets

Each year there’s always a crop of new diet plans that pop up in the media – all of which claim weight loss or better health and a handful of which become overwhelmingly popular by intrigued consumers – and this year didn’t disappoint. Here are some of the top searched diets this year: the Raw Foods Diet, the Ketogenic Diet, the Alkaline Diet, the Dukan Diet, and Whole30.

While it’s easy for health professionals like myself to roll their eyes at new fads, I’d be lying to say that I’m not one of those interested consumers. So when Cooking Light asked me to review this year’s top diet trends, I jumped on it. Here’s my research-based, bottom-line take on each.

The raw foods diet centers around the premise that cooking destroys nutrients, as well as enzymes found within each food, that are needed for digestion and disease prevention. For optimal health, all (or mostly all) foods should be consumed raw or below 115 degrees. Some raw food diet followers are vegans, eating only plant-based foods such as fruits, vegetables, nuts, seeds, grains, and legumes, while others add in a few animal-based products such as unpasteurized milk and cheese, raw fish, and some raw meat. Anything cooked, processed, pasteurized, irradiated, or in other words, not in its "natural state" is off-limits.

The Good: As a busy mom of two, the main positive that jumped out to me was not having to cook. But after thinking about it, I realized preparing raw food in different ways might be even harder – not to mention being unable to rely on convenience items when in a pinch. The only other positive I found was that the eating plan includes no added sugars, colorings, additives, or chemicals, and is low in sodium and high in potassium.

The Bad: Eating only raw foods makes it very hard to get in enough daily energy or nutrients, so if continued, weight loss (including some lean body mass), fatigue, low energy, and nutrient deficiencies are highly likely unless intake is carefully planned. There’s no reliance on convenience foods, and most restaurants don’t comply with the eating guidelines, unless they're specifically a "raw food" restaurant. Additionally, consuming unpasteurized dairy is not recommended due to potential pathogens, especially for children and those with compromised immune systems.

Bottom Line: Avoid the headache of learning to “cook” raw. This eating plan is one to skip due to nutritional inadequacy and potential health risks– not to mention the fact that there’s little research to support its health claims.

Think of the Ketogenic Diet as a low-carb version of an already low-carb diet, so low in carbs that most variations of the diet average only about 5 percent of calories from carbs – approximately 25 grams if eating around 2,000 calories. The goal of this diet is to put the body in a state of ketosis, something that’s suggested to increase the body’s breakdown of fat stores for energy due to a lack of glucose from carbohydrates. Meals are based around meats, poultry, fish, eggs, higher-fat dairy (like butter, cheese, and cream), healthy fats (like oils, nuts, seeds, and avocados), and vegetables that are low in carbohydrates (like green vegetables, tomatoes, onions, squash, peppers, etc.). All starchy vegetables, grains, fruits, dairy such as milk and yogurt, natural and refined sugars and sweeteners – or anything that would increase carb intake to above 5 percent of calories – should be avoided.

The Good: I was happy to see that most versions of the ketogenic diet encourage healthier cuts of animal proteins and the use of heart-healthy oils and fats – something that isn’t always done in low-carb diet plans. Another plus is the central role that vegetables play in almost every meal and snack. If a variety are chosen, then it’s likely one could get close to their recommended fiber and vitamin intakes. Lastly, ketosis suppresses appetite, something that could help with hunger and cravings, particularly if carb-heavy foods are an issue.

The Bad: Ketosis is considered a survival mechanism of the body when glucose is low – not necessarily a desirable state for the body to be in full-time – and the first few days are often accompanied by “keto-flu”, symptoms like headaches and lack of energy. Vegans will find following a ketogenic nearly impossible since plant-based proteins like beans are also sources of carbs and off-limits, and since nuts, seeds, and low-carb veggies can’t provide all essential amino acids. Vegetarians that eat dairy and/or eggs will find it challenging, but a little more doable, although the lack of food variety raises potential issues for nutrient deficiencies. On a personal note, the thought of not eating any fruit makes me sad, not to mention question the healthfulness.

Bottom line: This is why you never knock a diet until you look at the research: there’s actually a lot of published research (in reputable journals) suggesting that following a ketogenic diet has positive effects on blood sugar, insulin levels, insulin sensitivity, and triglycerides, and that ketogenic diets may be more effective for weight loss in certain individuals. While it’s hard for me to advocate for any plan that rules out whole food groups, the research is intriguing to say the least.

Get ready to go back to high school chemistry class because the premise behind the alkaline diet is that foods impact the body’s internal pH level and that replacing acidic foods with more alkaline ones improves health and possibly prevents diseases like cancer. (As a quick refresher the pH scale ranges from 0 to 14; the more acidic a substance is the lower its pH value, and the more basic or alkaline a substance the higher its value.) The eating plan focuses on eating alkaline-promoting foods which include fruits, vegetables, beans, nuts, and seeds, and eliminating acid-promoting foods which include meat, poultry, fish, dairy, eggs, grains, and alcohol.

The Good: The alkaline diet is predominantly a plant-based diet that’s centered around healthy food choices – unprocessed foods, fruits, vegetables, nuts, and beans – while limiting less healthy ones like animal protein, refined grains, and alcohol. For many individuals, simply making these types of food choices is a step in a better direction health-wise, as its typically lower in sodium, saturated fat, and sugar, and higher in potassium and fiber.

The Bad: The body is designed to constantly regulate its pH, and the pH varies in different parts of the body (consider the pH of the stomach with hydrochloric acid). There is little, if any, research to suggest that food choices impact the overall pH of the body, as well as little to support that alkaline food choices improve health. Some followers go as far as using pH test strips to check the pH of their urine – not a daily activity that I really want to take on, nor one that appears to any real scientific basis. Finally, knowing which foods are acidic, neutral, or alkaline is not something intuitive or listed on the label – meaning memorizing “acidic” and “alkaline” food choices is necessary to follow the eating plan.

Bottom line: If following an alkaline diet helps you make healthier, less processed food choices, then go for it. However, the benefits outside of that are questionable to say the least. Use the money for urine testing strips towards a gym membership or retirement savings instead.

The Dukan Diet is a popular low-carb, high-protein eating plan that touts quick weight loss and no carb counting. The eating plan is divided into four stages with the first two being where weight loss occurs and the last two focusing on maintenance. Stage 1 lasts for 2 to 5 days and calls for eating only “natural pure protein foods” along with 1 ½ tablespoons of oat bran and lots of water. Stage 2 adds some low-carb vegetables in with protein foods. Once desired weight is reached, then Stage 3 and 4 slowly incorporate minimal amounts of fruits, starchy vegetables, and cheese. The high-protein foods encouraged include lean meats, lean pork, skinless poultry, fish, non-fat dairy, eggs, and soy proteins like tofu.

The Good: If you’re a meat lover and you’ve got the financial means to buy lots of lean protein, then this may be an ideal eating plan for you. Two positive aspects in the Dukan diet are that it encourages regular exercise (something you don’t always see in low-carb plans) and that it provides followup with a maintenance plan, hopefully reducing the risk of regaining any weight lost.

The Bad: You’ve got to eat animal protein – a lot of it – which means this rules out vegetarians and raises some health concerns since higher animal intakes are associated with some cancers. Also, the thought of choking down oat bran with my plate of chicken breast doesn’t sound the most appealing. Weight loss may be a result, but this type of restrictive eating plan is one that can often set people up for binges when they “fall off the wagon” with Dukan-style eating.

Bottom line: This might be option for a meat-lovers looking for a very rigid, low-carb diet plan, but there’s healthier eating plans (including lower-carb ones) that will likely lead to better long-term weight-loss success.

Think of Whole30 as a month-long eating reset where you focus on eating only whole, unprocessed foods and cutting out all added sugars, artificial sweeteners, alcohol, grains, most legumes and peas, soy products, dairy, and processed foods with certain additives. The Whole30 concept is based on the premise that our highly processed, modern diets trigger inflammation, hormone imbalances, and subtle food intolerances that may be having a cascading effect on health, as well as appetite and food choices. By eating “clean” for 30 days, an individual can then assess what foods they really miss, as well as identify potential effects that foods may have on their body when adding them back. Foods during the 30 days include all vegetables, fruits, nuts and seeds (including nut milks and nut butters), eggs, fish, meat, poultry, and some oils and fats.

The Good: For the most part, the food choices provide a framework for nutrient-dense, whole foods to become the focus of your diet. This eating plan isn’t called a weight loss plan, since the emphasis is more on restoring health and balance in the body, but most individuals do lose some weight. The guidelines also mimic what research suggests be done to reduce inflammation and chronic diseases risk. I’ve found a temporary “reset” with whole foods similar to this to be really helpful after eating periods of less healthy eating like after the holidays or vacation because 1) your body is usually craving whole foods at that point and 2) it’s usually eye-opening realizing how many chemicals, added sugars, and other less health components you’ve been consuming.

The Bad: A lack of calcium and vitamin D intake is my only major concern from a nutrition standpoint, and these could be met other ways with proper planning. Temporarily removing dairy as part of a bigger plan is often a helpful approach to calm the body and identify food intolerances and issues, but most individuals can usually add all or some dairy components back after 30 days. My other issue is that legumes are off-limits, something that I have a hard time justifying as foods I need to avoid – particularly peanut butter.

Bottom line: The 30-day timeframe makes drastic eating changes (many that we know we all need to do) seem doable, and meal plans typically provide adequate energy. I’ve done a few “rounds” of Whole30 or similar plans, and while I regress to many of my old eating habits, I do seem to incorporate one or two healthy takeaways each time I do it.

• Westman, et al. "The effect of a low-carbohydrate, ketogenic diet." Nutrition & Metabolism, 2008.
• P.A. Dyson, S. Beatty, D. R. Matthews. "A low-carbohydrate diet is more effective in reducing body weight." Diabetic Medicine, 2007.
• Manninen, Anssi. "Very-low-carbohydrate diets and preservation of muscle mass." Nutrition & Metablism, 2006.