Pegan, Low FODMAP, Whole 30: How To Know Which Trendy Diet Will Give You The Results You Want

Registered Dietician By Amy Shapiro, M.S., R.D., CDN
Registered Dietician
Amy Shapiro M.S., R.D., CDN, is a registered dietician and the founder and director of Real Nutrition.
Pegan, Low FODMAP, Whole 30: How To Know Which Trendy Diet Will Give You The Results You Want

Photo by Anna Pustynnikova

From keto to paleo, gluten-free to dairy-free, and vegetarian to vegan, which one is right for you? In my eleven years as a registered dietician in New York City, I often see clients who are on the wrong diet for their specific goals—or who are looking for a one-size-fits-all solution. The number one thing to know? The diet that suits you is likely different than the one that worked for your friend or co-worker. Below, I’ve outlined what these diets are and what they entail so you can make an educated decision on which might be right for you and your lifestyle:

Whole 30

Meet the ultimate elimination diet. This program is ideal for people who have unidentified food allergies and who feel like they have overindulged in dessert and alcohol. Cut out gluten, dairy, soy, legumes, sugar, processed foods, alcohol, and pretty much anything on a food label that you cannot pronounce. After 30 days, you can reintroduce foods one food group at a time to see how it affects your GI tract and digestion. Ideally, you’ll commit to omitting the foods that don’t agree with you while eating the foods that do.



Also known as the hunter-gatherer diet of our ancestors, this trendy diet cuts out everything from sugar to dairy to processed foods and also most grains, white potatoes, and legumes. Basically, anything that doesn’t come naturally from the earth. But meat is fair game. Although limiting, paleo will increase the number of nutrients you get (thanks to eating more whole foods) and will be sure to lower your glycemic load.


For this diet, you decrease your carbohydrate intake (5 to 10 percent of daily calories) and rev up the healthy fats (60 to 75 percent), with a moderate amount of protein (15 to 30 percent). This allows the body to start using ketones (the by-product of fat) as its primary source of fuel instead of glucose (the by-product of carbohydrates), and, therefore, your body burns more fat. Not only has this diet been shown to help with weight loss, but it has also been shown to decrease tumor growth, help with epilepsy, and manage diabetes, metabolic syndrome, and neurological disorders.


Food combining

This diet focuses on pairing certain macronutrients and keeping others apart. Generally speaking, fruit should be eaten alone on an empty stomach, protein should be paired with vegetables (NOT with starches or fats), and starch can be enjoyed with fat and vegetables. This is because different foods are digested at different rates, and slow-digesting foods cause a backup in the GI tract. Also, different foods require different pH levels to be digested properly. The body cannot digest foods that require different pH levels at the same time the right way. Reported benefits have included weight loss, improved digestion, boosted energy, better skin, and more efficient nutrient absorption; however, the findings have been inconclusive.


People who try this diet tend to suffer from GI discomfort that isn’t easily alleviated through simple dietary changes. These symptoms are often caused by the inability of the small intestine to absorb certain sugar chains such as fructose, lactose, and sugar alcohols. Often individuals with IBS or other GI disorders will implement this diet to alleviate gas, bloating, pain, pressure, and reflux. Trying a FODMAP diet means eliminating short-chain carbohydrates that are poorly absorbed in the small intestine. This includes oligosaccharides (wheat, rye, legumes, some fruits and vegetables), disaccharides (milk, yogurt, soft cheese), monosaccharides (figs, mangoes, honey), and polyols (blackberries, lychees, low-calorie sweeteners).



This diet is a MUST for those living with celiac disease (an allergy to gluten, the protein found in wheat). Other individuals may benefit from this diet, as gluten is thought to cause inflammation in the body, especially for those who have inflammatory and autoimmune diseases. Additionally, some research shows removing gluten may lessen the effects of ADD/ADHD. Some individuals generally feel less bloating, gas, and discomfort when off gluten, but others use this diet as an easy way to avoid excess carbohydrates. If that is the case, do your research, because many packaged GF foods are high in sugar and overly processed. "Gluten-free" does not automatically equal "healthy."


People who are lactose intolerant will feel better when they remove most dairy from their diet. However, removing dairy has been shown to have many other health benefits including improved digestion, weight loss, reduced exposure to added antibiotics and hormones, and improved skin integrity. Additionally, some individuals benefit from the removal of dairy during allergy, cold, and flu season as it increases dampness in the body (according to traditional Chinese medicine) and therefore creates more mucus. And don’t worry: You’ll get more than enough calcium through other foods including plants, nuts, and seeds.



This is the "newest" of these trendy diets, thanks to Dr. Mark Hyman and his book, Food, What the Heck Should I Eat? This diet is basically a combination of a paleo and vegan diet with an emphasis on whole plant foods and organic meat sources. Here, you basically get the best of both worlds! This diet has been shown to decrease inflammation and may lead to a healthier lifestyle overall.

Intermittent fasting

This diet depends not on what you eat but on when and how much you eat. People on this diet fast for different lengths of time, depending on the method they choose. When done the right way, it’s been shown to regulate blood glucose levels, control blood lipids, reduce the risk of diseases, and manage body weight.


My No. 1 choice?

Personally, I am a big believer in the pegan diet, as I try to eat mostly plants. I’ve also enjoyed food combining and have felt great when intermittent fasting but found that didn’t work well with my lifestyle (and I missed eating when I woke up!). I do not suffer from IBS or GI distress, so FODMAPS doesn’t apply to me, but that doesn’t mean it isn’t a great plan.

Want to know more about the pegan diet? Founder Mark Hyman explains it all here.

And do you want your passion for wellness to change the world? Become A Functional Nutrition Coach! Enroll today to join live July office hours.

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