Shaun Ward MSc ANutr
The slow-carb diet is a very similar alternative to the ketogenic diet.
It was created by Tim Ferriss, a popular podcaster, author, entrepreneur, and investor. Tim previously had success in releasing the 4-hour body book, where he argues that only 4 hours a week are needed in the gym to achieve your health and fitness goals.
This most recent addition to his book collection follows along a similar path, yet focuses more on nutrition as opposed to exercise.
What Is The Slow Carb Diet?
Sharing a common approach to his previous book, Tim once again has the motive to create methods that get people the best results whilst putting in the least amount of effort. It is a very minimalistic approach to diet and nutrition, and clearly targets individuals with a hectic lifestyle.
He focuses on providing people with only a few key rules to follow, believing that its simplicity will lead to dietary compliance and results.
While following the diet, you can only eat from a small list of “allowed foods” for 6 consecutive days. On the 7th day, a cheat day is allowed where all food groups can be consumed without worry.
The 5 food groups that are allowed include; animal protein, vegetables, legumes, fats, and spices. Calorie tracking is not advised on this diet, and people are able to consume as much as meat and vegetables as they desire.
All other food groups, such as fruit and wholegrains, are completely eliminated. Like the ketogenic diet, the slow-carb diet seems to be based on the premise that eating a lot of protein and very few carbohydrates could aid weight loss by increasing fat metabolism, reducing feelings of hunger, and reducing fat stores.
In addition to specifying the 5 food groups, Tim also states 5 key rules for the diet:
- Avoid "White" Carbohydrates – The idea here is to avoid all carbohydrates that have a high-glycemic index and spike blood sugar levels. The only exception to this rule is for resistance-training athletes who can consume a moderate amount of simple carbohydrates in the 30-minute post-workout period to replenish energy stores.
- Keep Meal Options Limited – Tim recommends sticking with a small number of food and meal options as this will unconsciously reduce overall energy intake and avoid snacking and binge eating.
- Do Not Drink Calories – Time to bin the orange juice and milk, as only water, unsweetened tea, coffee, or other calorie-free drinks are allowed. Clearly the diet takes a food first approach, which can only be praised.
- Do Not Eat Fruit - This idea is based on the theory that fructose hinders weight loss by increasing the amount of fat in the blood and blunting the body’s ability to target and burn fat.
- Include 1 Cheat Day a Week – This day is a chance for people to consume the foods they may have craved throughout the week and overcome any nutrition-related stress. It is also partly based on the fact that some evidence indicates that dietary “refeeds” (infrequent days with high calorie intake) when in a dieting phase may effectively stimulate ones resting metabolic rate and increase blood levels of the satiety hormone called leptin .
In terms of supplements, Tim states these aren’t necessary, however he does recommend a few supplements for those looking to really accelerate their results.
- Potassium, magnesium and calcium to replace lost electrolyte stores
- Policosanol, alpha-lipoic acid, green tea flavanols, and garlic extract to aid fat burning processes
All these supplements are recommended to be taken alongside main meals.
The Potential Benefits of The Slow Carb Diet
Below is a list of every potential benefit that's backed by credible scientific research:
It Will Help With Weight Loss
As common sense would suggest, limiting the variety of foods that are allowed during a weight loss plan may help people subconsciously consume fewer calories and maintain long-term weight loss .
For example, the slow-carb diet also avoids the consumption of sugary foods which will help to avoid “empty calories” that provide no nutritional value .
Although the slow carb diet has not been directly studied, based on the similarities to the ketogenic diet and paleo diet that have been studied in-depth, a 10-15lb reduction in bodyweight can be expected in a 2-6 month period   .
However, there is nothing inherently special about low-carbohydrate diets, and weight loss is purely as a result of maintaining a negative energy balance for an extended period; consuming less energy (calories) than expended per day.
Improved Control of Blood Glucose Levels
The blood glucose level is the amount of glucose present in the blood. Under normal circumstances this amount is tightly regulated, however diabetes is a disease characterized by a persistently high amount of glucose in the blood, due to an inability to regulate and clear glucose from the bloodstream.
Low carbohydrate diets are frequently seen to help stabilize blood glucose levels .
This is because carbohydrates are mainly responsible for large increases (and decreases) in blood glucose levels. By replacing the majority of carbohydrates with dietary fat, which have a very minor effect on blood glucose levels, this will help greatly with stabilizing fluctuations daily blood glucose levels.
This is proven in an array of studies, with low carbohydrate diets consistently improving blood glucose levels and insulin sensitivity (the ability to clear glucose from the blood) more than low fat diets .
As a side benefit to this, better control of blood glucose levels will work to reduce the amount of chronic inflammation in the body, and reduce the amount of advanced glycation end products in the blood. Advanced glycation end products are harmful compounds that are formed when sugar combines with fat in the bloodstream .
The Negatives of The Slow Carb Diet
Below is a list of everything we believe could be viewed as a negative:
Potential Micronutrient and Fiber Deficiencies
As the slow-carb diet recommends avoiding all fruits and certain vegetables, it could restrict the intake of beneficial substances like vitamins, minerals, antioxidants, and fiber .
For example, the Paleo diet has shown to increase the chances of deficiency in folate, magnesium, fiber, vitamin E, potassium, flavonoids, selenium, lignans and phytosterols. Similarly, the ketogenic diet may lead to low intakes of magnesium, copper, phosphorus, phytonutrients, vitamin C, and antioxidants.
With the slow-carb diet having many similarities to both these diets, people may be at risk of similar deficiencies that can simply be avoided by the inclusion of other food groups in a more well-balanced diet.
It is not logical to unnecessarily restrict certain food groups that contribute towards a healthy diet.
Reduced Athletic Performance
All sporting activity which revolves around strength, speed or endurance will ultimately be heavily reliant on carbohydrate availability for peak performance.
When carbohydrate stores (glycogen) in the muscle are depleted, this is a major trigger for the onset of fatigue and a reduced power output . The reason for this is because carbohydrates are located being directly within muscle fibers, close to the mitochondria, where they act as an efficient source of energy to support high-energy demands during intense activity.
In addition, the longer an athlete remains on a severely carbohydrate-restricted diet, the more incapable they become at utilizing carbohydrate stores when needed. This is due to a downregulation of the regulatory proteins involved in carbohydrate metabolism when dietary carbohydrate is restricted for long periods.
For both the reasons mentioned, long-term carbohydrate restriction in athletic populations is not a good idea from a sport nutrition perspective .
In general, the slow carb diet is another version of a carbohydrate-restrictive diet that does a good job at lowering caloric intake and focusing on natural wholefoods.
Most people will likely see weight loss and health improvements on such a diet, especially if they were on a standard western diet high in sugar, saturated fat, and omega-6 fatty acids.
However, the diet unnecessarily restricts some healthy food groups such as fruit and wholegrains which are recommended to contribute towards a healthy diet. In addition, the severe restriction of carbohydrates will not be suitable for athletes or anyone with high nutritional demands.