The diet calls for more veggies—but almost entirely forbids fruit.

By Cynthia Sass, MPH, RD
June 08, 2020
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Low-carb diets aren't exactly a novel idea. The combination of reducing carbohydrate intake—and increasing the amount of protein and vegetables you eat—has been a popular weight-loss practice for some time. But while they're generally effective for weight loss, one of the top criticisms for low-carb diets is that they're too restrictive.

The Slow-Carb Diet is yet another carb-limiting approach. While it’s not new, it has resurfaced in popularity. Here’s a look at what the diet entails, its potential pros and cons, and my thoughts as a registered dietitian about whether it’s worth a go.

What is the Slow-Carb Diet?

The Slow-Carb Diet was created by Timothy Ferriss, author of the book The 4-Hour Body, back in 2010. Ferriss, who is not a doctor, dietitian, or health professional, claims that the diet “hacks” the human body, and can result in rapid weight and fat loss.

The diet is essentially broken up into six days on, followed by one "cheat" day off, during which you can eat and drink whatever you want. During the first six days, you eat four meals a day based on five food groups: animal protein, vegetables, legumes, fats, and spices. You can eat as much as you'd like from the first three food groups, and small amounts of food from the remaining two.

The diet’s strict rules involve avoiding white carbs, including processed products like bread and pasta, as well as all fruit (with the exception of avocado and tomato), dairy (although cottage cheese and whey protein powder are OK), and fried foods. Meal repetition is encouraged during the six days on the diet. Water, unsweetened black coffee and tea, and up to 16 ounces of diet soda per day are sanctioned, as are a few glasses of dry red wine daily.

As for timing, breakfast should be consumed within an hour of waking up, and the remaining meals should be spaced about four hours apart. Filling up on low carb veggies is encouraged, and followers should consume at least 30 grams of protein at breakfast and 20 or more grams of protein in each of the remaining meals. The breakfast protein target is encouraged even on the cheat day. The diet suggests supplements to enhance weight loss, but they are not mandatory.

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What are the pros of the Slow-Carb Diet?

The Slow-Carb Diet does have some pros, including the emphasis on vegetables, the inclusion of plant protein from pulses, like beans and lentils, and the liberal use of antioxidant rich herbs and spices.

In addition, eating patterns that reduce the intake of added sugar and refined grains are also linked to lower risks of obesity, type 2 diabetes, heart disease, and other chronic illnesses.

While weight loss may also be a pro, that’s only true if it’s sustained (see more on that below). Another potential benefit is settling into a pattern of eating four times per day, which may help end an erratic pattern of either nibbling all day or waiting too long to eat and then overeating.

What are the cons of the Slow-Carb Diet?

The cons of the Slow-Carb Diet are things you’ve likely heard before. The plan is too limited, and cuts out nutrient and fiber rich whole grains, fruit, and starchy veggies, like potatoes.

These health protective foods deserve a place in your daily diet, and can be incorporated while you simultaneously shed pounds. In fact, various studies have shown that both whole grains and fruits are linked to weight loss, not gain.

All all out cheat day once a week can also present a problem—rather than learning how to incorporate can’t-live-without goodies as part of any balanced day, full-on cheat days can lead to overindulging in ways that leave you feeling bloated and lethargic for a few days. It can also reinforce a disordered “on” versus “off” eating pattern that can negatively impact mental health and interfere with a healthy social life.

The bottom line about the Slow-Carb Diet:

In my opinion, this now decade-old diet is showing its age with its simplistic rules, emphasis on animal protein, avoidance of plant-based food groups, allowance of diet soda, and "cheat" days.

Weight loss has evolved — it's now more inclusive of overall nutrition and food enjoyment, with approaches that abandon an "on/off" diet mentality and focus fostering lifestyle habits. In my 20 years of counseling clients, one thing I have witnessed time and again is that weight loss is personal. The approach that works for you long term should align with your gut instinct, make you feel good physically, emotionally, and socially, and become a healthful pattern, rather than an imposition.

Cynthia Sass, MPH, RD, is Health's contributing nutrition editor, a New York Times best-selling author, and a private practice performance nutritionist who has consulted for five professional sports teams.

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