For years, several weight-loss diets have emphasised protein while minimising carbohydrates. But while the slow-carb diet also follows that approach, it offers detailed guidance on foods to eat and avoid, along with supplements to consider.
Touted as an easy way to lose weight without counting kilojoules or intense exercise, the diet has gained a loyal following. However, experts caution that its restrictive nature may not be suitable for everyone.
The slow-carb diet was created in 2010 by entrepreneur and lifestyle guru Timothy Ferriss, who wrote The 4-Hour Body. The book was a New York Times bestseller, and the slow-carb diet quickly gained popularity.
While the slow-carb diet shares some similarities with other high-protein diets like keto, it’s noticeably different. Here’s what the slow-carb diet involves and whether dietitians think it’s worth trying.
What is the slow-carb diet?
The slow-carb diet is an eating plan based on five rules. “It’s not unreasonable to expect to lose 4.5–9 kg of fat,” Ferriss wrote of the diet on his blog. “This is true even without exercise.”
The slow-carb diet leans into the idea that small changes can lead to big results. Ultimately, it promises to help people burn fat and lose weight.
Ferriss provides extensive details about the diet, including a list of foods that are allowed over six days. On the seventh day, followers are encouraged to have a free-eating day where they can enjoy whatever they like.
During the six main days, followers are encouraged to eat several meals daily, focusing on five key food groups: animal protein, vegetables, legumes, fats and spices. Refined carbohydrates, fruit and high-energy drinks should be avoided.
Each meal should focus on animal protein, vegetables and legumes, and these can be eaten in unlimited amounts. Ferriss also suggests taking certain supplements but notes that they are not a required part of the diet.
How to follow the slow-carb diet
The slow-carb diet has five rules that followers are expected to adhere to:
Avoid ‘white’ carbohydrates
That means cutting out carbs that can be white, including bread, pasta, rice, potatoes and grains.
Eat the same meals
You don’t need to eat the exact same thing at every meal, but the diet encourages sticking to a few go-to dishes, particularly for breakfast and lunch.
Avoid drinking your kilojoules
The diet promotes drinking plenty of water. Followers can also have unsweetened tea, coffee or other calorie-free drinks but should avoid beverages that contain significant kilojoules. The exception? One to two glasses of dry red wine per night.
Skip fruit
Ferriss claims that fructose, the natural sugar in fruit, can increase blood fat levels, so he advises cutting it out entirely.
Have one cheat day a week
Ferriss encourages followers to “go nuts” on this day, enjoying whatever they like
What foods can you eat on the slow-carb diet?
The diet divides foods into five groups: protein, legumes, vegetables, fats and spices. Ferriss suggests picking a few foods from each group and sticking with them. His reasoning? The more variety you allow, the higher the chance of straying from the plan.
The slow-carb diet recommends building your diet around these foods:
Proteins
- Eggs
- Chicken (breast or thigh)
- Fish
- Beef (preferably grass-fed)
- Pork
- Lamb
Legumes
- Lentils
- Black beans
- Pinto beans
- Red beans
- Soybeans
Vegetables
- Spinach
- Mixed vegetables (broccoli, cauliflower or any other cruciferous vegetables)
- Sauerkraut, kimchi
- Asparagus
- Peas
- Broccoli
- Green beans
The diet suggests limiting these foods:
Fats
- Butter
- Olive oil (for cooking)
- Grapeseed or macadamia oil (for cooking)
- Nuts
- Ghee
- Non-dairy creamer (up to 2 teaspoons a day)
Spices
- Salt
- Garlic salt
- White truffle salt
- Herbs
Foods to avoid on the slow-carb diet
While the slow-carb diet doesn’t put limits on how much you can eat, it does suggest avoiding these foods:
Fruits
This includes both whole fruit and fruit juice (though they are allowed on the cheat day if desired).
Dairy products
While butter and ghee are allowed, traditional dairy foods like milk, cheese and yoghurt are not included.
Refined carbohydrates
Ferriss calls these “white” carbs, including bread, pasta, rice, potatoes and grains.
What is the slow-carb diet cheat day?
The slow-carb Diet includes a designated free-eating day. During this day, Ferriss says you can eat whatever you like. He suggests picking one specific day a week—his recommendation is Saturday—to fully enjoy your favourite foods.
Slow carb diet supplements
Daily supplements are not required on the slow-carb diet, but Ferriss suggests several to help fill nutritional gaps and support weight loss, including:
- 99 mg of potassium
- 400 mg of magnesium
- 1,000 mg of calcium
- 20 to 25 mg of policosanol
- 100 to 300 mg of alpha-lipoic acid
- 325 mg of epigallocatechin gallate
- 200 mg of garlic extract
Slow-carb diet benefits
There are a few potential benefits to following the slow-carb diet. Cutting out refined carbohydrates eliminates common calorie sources and reduces blood sugar fluctuations that can trigger overeating and cravings, says registered dietitian Scott Keatley.
The diet’s strict structure can lead to weight loss, says registered dietitian and nutritionist Keri Gans. “Almost any time you eliminate an entire food group, such as fruit and dairy, you will lose weight,” she explains.
The focus on whole, high-protein foods may help some people feel fuller for longer while preserving muscle, Keatley says. “It also removes many calorie-dense processed foods, which can lead to initial weight loss,” he adds.
The diet also encourages plenty of vegetables and legumes, which are packed with fibre, vitamins and minerals, Gans points out. “For some, the simplified meal plan is a bonus—fewer choices can make it easier to stay on track,” she says.
Slow-carb diet drawbacks
Nutritionists point out several downsides to this diet. “This approach oversimplifies nutrition and unnecessarily restricts nutrient-rich foods like fruit and dairy, which provide essential vitamins and minerals,” Keatley explains.
The supplements are likely included because the diet lacks key nutrients, he adds. “While supplements help, they can’t fully replace the wide range of nutrients found in whole foods, which raises concerns about the diet’s long-term sustainability,” Keatley says.
While Gans acknowledges the diet’s structure may be helpful at first, she warns that the lack of variety may eventually lead to boredom and make it harder to follow. “This will turn into a con as repetition often causes people to give up,” she adds.
Gans also believes removing entire food groups is “misguided.”
Sample slow-carb diet meals
There is no calorie counting on the slow-carb diet, and Ferriss encourages followers to eat freely within the allowed foods. However, he recommends selecting three to four meals and sticking to them for at least the first two weeks. Here are some examples:
Breakfast
Three scrambled whole eggs, lentils and spinach
Lunch
Grass-fed organic beef, pinto beans, mixed vegetables and extra guacamole
Dinner
Salmon, asparagus (or lentils) and coconut cauliflower curry mash
Is the slow-carb diet safe?
In the short term, the slow-carb diet may be safe, but dietitians raise concerns about its impact on long-term health.
“For most individuals, the slow-carb diet is not a sustainable or optimal approach to weight loss,” Keatley says. “While it may deliver short-term results, its restrictive nature and reliance on supplements make it less appealing compared to balanced dietary patterns that include a variety of nutrient-dense foods.”
Gans also does not recommend this diet. “There are far better, less restrictive and healthier options available that support weight loss without compromising a person’s wellbeing,” she says.
Dietary supplements are intended to complement the diet but are not a substitute for whole foods. They are not medicines and are not designed to treat, diagnose, prevent or cure diseases. Be cautious when considering dietary supplements, particularly if you are pregnant or nursing. Also, seek medical advice before giving supplements to a child, unless recommended by their healthcare provider.
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