If all the “New Year, New You” messaging has you thinking about slimming down and getting healthier, you might be considering one of the trendy diets making the rounds.
As a registered dietitian, I often cringe at the mention of diets. Most diets are only a temporary fix. The key is to find an eating plan and make lifestyle changes that work for you over the long run.
I’m a firm believer in sustainable, realistic, long-term behavioral changes that include eating small protein-rich meals and snacks through the day to optimize energy, alertness, focus and body composition.
Still, diets are popular and they can help jumpstart one on a healthier path, so here’s the rundown of four hot-right-now diets with merit.
Before embarking on any new diet, check with your physician, especially if you have a history of eating disorders or chronic health issues such as diabetes, high blood pressure or heart disease.
Consider working with a registered dietitian who can guide you in developing a personalized nutrition plan that’s tailored to your health needs, preferences, lifestyle and budget.
A registered dietitian also can help identify the effective components of certain diets and help you steer clear of the elements that may be detrimental. See related stories in each section for more details on the diet plans.
What it is: Intermittent fasting is less about the foods we eat and more about when we eat them. There are many different intermittent fasting methods, all of which divide days into eating periods and fasting periods. Daily fasting windows, for example, can range from 12 hours to a more extreme 20 hours daily. Many plans recommend a three-hour fasting window between the day’s last meal and bedtime.
What’s allowed during the fasting window: Water, sparkling water, green tea, coffee, chicken broth or vegetable broth.
What’s allowed during the eating window: This will vary based on individual preference, but is best when centered on real, whole foods including lean proteins, plant-based fats, vegetables, fresh-pressed vegetable juices, fresh fruits, whole grains, legumes, bone broth and lower-sugar dairy and dairy alternatives, like plain Greek yogurt and unsweetened almond milk. Intermittent fasting is not an excuse to binge during the eating window.
What’s not allowed at any time: For those opting to go the route of intermittent fasting, my recommendation is to also avoid added sugars (e.g. maple syrup, honey, agave), artificial sweeteners like Splenda, aspartame and acesulfame potassium, and white, refined, processed carbs like white breads, potatoes, pasta and rice.
My take: I like the flexibility in food options that intermittent fasting offers. Unlike the Keto diet, which requires tracking our “macros” (carbs, protein, fat) and restricts higher-carb foods like fresh fruit and fiber-rich whole grains, and also unlike Paleo or Whole 30 that eliminate dairy (including Greek yogurt) and entire categories of foods, intermittent fasting allows for any and all types of foods, as long as they’re consumed during the eating window.
And I really like the emphasis on leaving a three-hour window between the last meal or snack and bedtime. Not only can it help to avoid acid reflux and morning bloating, it also puts mindless nighttime snacking in check, a habit that has a vise grip on many.
A word of caution: This diet should be avoided by individuals with certain chronic health conditions as well as those with a history of eating disorders.
What it is: There’s no counting or weighing or measuring with Whole30. It’s a 30-day program centered on real, whole foods, a temporary elimination diet designed to serve as a reset button to help retrain habits and taste buds.
Whole30 shares a lot of similarities with the Paleo diet, with two key differences:
Paleo is intended to be a long-term way of eating, while Whole30 is designed to be a 30-day reboot for our bodies, our brains and our habits.
Paleo and Whole30 eliminate most of the same foods, but Whole 30 takes it even further, also limiting sugar, including honey, maple syrup and coconut sugar.
What’s allowed on Whole30: Proteins including meat, fish, poultry, seafood and eggs. Fruits and vegetables. Nuts and seeds, including almond butter and sunflower seed butter. Fats including coconut oil, olive oil, avocado oil. Salt, vinegar, herbs, spices and seasonings. Beverages including water, tea, bone broth, sparkling water. Ghee or clarified butter are the only source of dairy allowed.
What’s not allowed on Whole30: No sweeteners, including artificial sweeteners. No alcohol in any form, not even for cooking. Grains and legumes of all types are off limits; this includes peanuts and peanut butter. No soy, soy sauce, miso, tofu, tempeh or edamame. No cow, goat, or sheep’s milk products like milk, cream, cheese, kefir, yogurt, sour cream, ice cream, or frozen yogurt. No carrageenan, MSG, or sulfites. No baked goods, junk foods, or treats, even with “approved” ingredients.
My take: I like the Whole30 approach as a type of “reset” button and as a way to identify potential food triggers that may be linked to inflammatory, mood or gastrointestinal problems, cravings and other weight issues.
While the Whole30 approach may not be long enough or specific enough to target the full spectrum of health and medical issues, the 30 days can give us a good starting point to see how these changes to our diets affect how we feel. It’s long enough to start to see and feel very real benefits, and it serves as incentive and inspiration to continue with “cleaner” eating habits.
What it is: “Keto” is short for a ketogenic diet. In my experience, Keto is one of the most talked-about but least understood diets on the market. People say they are “going Keto” when they are limiting carbs, but that doesn’t necessarily mean they’re following a Keto plan.
The classic ketogenic therapeutic diet is a very high-fat, extremely low-carbohydrate and low-protein diet, calling for a 4:1 ratio of fat to combined protein and carbohydrate.
Carbohydrate and protein limits vary. The general rule of thumb for a keto diet is a maximum of 50 grams of carbohydrate daily, though many keto advocates recommend about half this amount. Protein goals are generally around 0.8 grams of protein per pound of lean body weight, with the rest of the calories coming from fat.
What’s allowed on a Keto diet: Fats of all types. Meat, fish, poultry and eggs. Nonstarchy vegetables and leafy greens, fresh or frozen; carbs from these vegetables need be factored into daily carbohydrate allotment. Dairy (organic, full-fat is recommended for keto diets; carbs need to be accounted for in daily total). No-calorie plant-based sweeteners like monkfruit, erythritol, stevia, including brands like Swerve and Truvia. Beverages with zero sugar or artificial sweeteners, including water, sparkling water, tea and coffee
What’s not allowed on a Keto diet: Starchy and/or refined carbs, including bread, rice, pasta, cereal, potatoes, pasta, rice or legumes, are pretty much off-limits entirely. Sugar of any type is out, including table sugar, brown sugar, honey, molasses, agave and coconut sugar. Only a small amount of fruit is allowed, mostly berries, because of their lower carb content.
My take: Research is mixed when it comes to the effectiveness of a ketogenic diet for fat loss, with several studies showing no significant difference in fat loss for ketogenic diets when researchers controlled for protein and calorie intake.
In my own experience as a registered dietitian, however, I have seen many clients experience positive results with a ketogenic diet.
One of the main advantages of following a keto diet is appetite control; we feel less hungry on the lower-carb keto plan, which generally results in a natural reduction in our calorie intake. Some of the research shows a daily reduction of 300 calories per day or more without really trying.
As a result, following a keto diet can help reduce cravings as well as drop body fat. Other benefits include improved blood sugar control, cholesterol, blood pressure and inflammation, all of which are likely due to the extra weight lost as well as following the lower-carb diet.
What it is: OPTAVIA is a diet plan by Medifast that’s centered on pre-packaged “Fuelings” (their word) consisting of pouches and boxes of meals and snacks that are made without artificial colors or sweeteners (their “select” line is also preservative-free).
There are three levels of OPTAVIA, and all clients are encouraged to connect with OPTAVIA coaches, available online or in person (OPTAVIA provides a list of coaches by region; note that these coaches are generally not registered dietitians, and are not required to have any formal medical or nutritional training).
Level 1, Optimal Weight 5&1. Five pre-packaged Fuelings with one real, whole-food “lean & green” meal daily. With 800 to 1,000 calories daily and 80-100 grams of carbs, this is the strictest of the three phases.
Level 2, Optimal Weight 4&2&1. Four pre-packaged Fuelings with two real, whole-food “lean & green” meals and one “healthy” snack daily. Approximately 1100 to 1300 calories and 85-100 grams of carbs per day.
Level 3, Optimal Health 3&3 Plan. Three pre-packaged Fuelings daily with three balanced meals daily. Calories vary based on individual needs. The suggestion by OPTAVIA is that one can stay in this phase indefinitely.
My take: I rank OPTAVIA 4th or 5th on this list, tied with keto.
Compared to the pure, real whole foods encouraged on Whole 30, Paleo and Intermittent Fasting, the concept of relying on purchasing shelf-stable pouches and boxes of foods from a designated OPTAVIA distributor seems a bit antiquated to me, one that creates an unnecessary reliance on pre-packaged foods.
We can create diets with a similar nutritional profile using the everyday foods that are available in our neighborhood grocery stores.
These pre-packaged food systems, however, give users a sense of confidence that the decisions are already made for them, which helps to eliminate guess-work and self-doubt. The social support surrounding OPTAVIA is also extremely helpful to those following the program.
Of the above four popular protocols, Intermittent Fasting and Whole30 are my top recommendations, followed by Keto and OPTAVIA.
As always, consult with your physician before beginning any new dietary regime. And keep in mind that a registered dietitian can help you sort through the different options and make sense of what will work best for you.