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What Is A Low Glycemic Impact Or Slow Carb Diet?

If you’re trying to lose weight or manage your blood sugar, you may have heard of the low-glycemic impact or Slow Carb Diet. But it also has many other health benefits beyond fat loss. In this article, we’ll explain what it is, how to do it, and its health benefits.

Fact checked by Nattha Wannissorn

What Is A Low Glycemic Impact Or Slow Carb Diet?

The Low Glycemic Impact diet focuses on eating food that minimizes the impact on blood sugar. The original version of this diet is based on the glycemic index, which was invented in the 1980s. Later on, the diet evolved to take into account the total amount of carbohydrate, or what’s called “glycemic load”, in foods. 

Even if you don’t have diabetes, understanding the impact of each food on your blood sugar and insulin levels will be a valuable tool for health optimization.  You cannot have great health and longevity without good blood sugar control. Elevated blood sugar levels accelerate aging.  

woman eating plain low glycemic yogurt with fruits

Because your brain is exquisitely sensitive to blood sugar fluctuations, stabilizing your blood sugar is essential for optimal cognitive performance and hormone balance. Also, improving your aesthetics is far easier with a higher level of insulin sensitivity. 

Slow Carb followers eat more protein and fibers, while reducing processed carbs. Overall, this combination increases the thermic effect of food. Also, the increased fiber composition can improve the microbiome towards the bacteria strains that favor metabolism.

One of the advantages of this diet is that you can manage blood sugar without needing to go through keto-adaptation. It can also be relatively easy to do and easier to adapt to different situations than ketogenic diets. For many, this diet is a gateway to ketogenic diets. 

Benefits Of A Slow Carb Diet

Better blood sugar control and weight loss

A 2019 meta-analysis of 54 studies shows that low-GI diets can improve blood sugar control and weight loss in people with diabetes and prediabetes.

Improves overall health and performance

Better managing your blood sugar benefits the whole body. It can also be better for your skin, brain, and mental health. Improving blood sugar and insulin sensitivity may not single-handedly cure these conditions, but it’ll make managing any chronic conditions easier. Also, healthy and stable blood sugar is crucial for optimal brain function. 

Clearer and less oily skin

According to the American Academy of Dermatology Association, blood sugar spikes and the resulting inflammation can make the skin oily, which can cause acne. A clinical study compared. 243 acne patients with 156 healthy controls. The authors found that the acne patients were significantly more insulin resistant than the healthy controls. They concluded that insulin resistance may contribute to acne. 

Better mental health and cognition

Type 2 diabetes correlates with neuropsychiatric disorders and dementia. Your brain constantly needs fuel, and significant fluctuations in blood sugar are bad for your brain. For anyone with mental health or cognitive issues, better blood sugar management through diet and exercise tends to improve symptoms. 

Slows down aging

Since glucose is an oxidative sugar, high blood sugar means more oxidation in your blood vessels and most tissues. This means accelerated aging. So, better blood sugar control is essentially anti-aging both in terms of appearance and disease risks.

group of people meditating

Is The Slow Carb Diet Magical For Weight Loss?

The premise of the Slow Carb diet is to manage blood sugar by focusing on foods that have lower glycemic impact. As a result, many people experience increased satiety and less sugar-related cravings, so they end up eating less food, which can lead to fat loss.

Ultimately in order to lose weight, you will have to be in a calorie deficit.  If you’re just stabilizing your blood sugar and eating at maintenance, then your weight will remain the same.  This is true for all diets.

However, I think most health experts would agree on one thing: keeping your blood sugar stable and within optimal range is important  for health reasons. 

The Original Slow Carb Diet 

The Slow Carb Diet is a low glycemic impact diet popularized by Tim Ferriss in his book The Four Hour Body. Ferriss made some modifications to make the diet easier to follow, which improved compliance and success rates, including:

  • Eating the same few meals over and over again (one of our key principles also)
  • Getting 30 grams of protein within 30 minutes of waking (protein for the win!)
  • Avoiding all white starchy carbohydrates, fruits, and dairy
  • Avoiding drinking calories (good strategy on any diet)
  • One cheat (refeed) day per week to enjoy your favorite foods. 
  • Use blood sugar support supplements (we suggest Blood Sugar Breakthrough)

This diet focuses on non-starchy vegetables, sources of proteins, legumes, nuts, and good fats. It tends to be low-carb and high-protein, with some variability in fats. Usually, legumes and pulses are the best types of carbs for this diet because they have very low glycemic load, high protein, and high fiber. So high-legume cuisines, like certain Mexican dishes, are good options. 

Participants are advised to eat to their appetite instead of counting calories. While eating to your appetite usually works very well for beginners or obese people, we recommend eventually tracking calories and macro breakdown as you progress with the diet.  Remember the rule of thumb: you don’t usually need to track or measure calories early on.  Just shifting diets is usually enough to naturally create a calorie deficit.

However, to achieve elite levels of leanness, you’ll eventually need to count and track calories.  That way you can ensure consistent progress and troubleshoot when the progress stalls. 

What’s The Difference Between Slow Carb, Paleo, And Keto?

  • The Slow Carb diet cuts out grains, refined sugar, and most fruits. It does include starchy vegetables, legumes, and beans to minimize glycemic impact. 
  • The Paleo diet does not include grains, legumes, or any refined sugars. However, there is no real limitation on carbs and you can consume fruits and starchy vegetables.
  • The Keto diet keeps a very tight control on carb consumption. 

Glycemic Index vs. Glycemic Load in the Slow Carb Diet

The Slow Carb Diet seeks to minimize the impact of food on your blood sugar (glycemic impact), which means low glycemic index AND glycemic load. 

A high glycemic index food spikes blood sugar higher than a low glycemic index food. The glycemic index compares the blood sugar increase of the food that contains 50 grams of carbohydrates to the blood sugar increase from 50 grams of pure glucose. 

However, to measure the glycemic index, the research subject needs to consume enough of the food to have 50 grams of carbohydrate. 

The problem with this model is that many foods have fast or high glycemic index carbs, but they have a low concentration of carbohydrates. It only takes into account the type of carbs, not the amount of carbs.

For example, carrots have a high glycemic index, but it takes a lot of carrots to get 50 grams of carbohydrates. Plus carrots have a lot of fiber. As a result, carrots typically have a low impact on blood sugar. 

That’s why glycemic load is a far better measurement than glycemic index.  Glycemic load is a more accurate measurement that takes into account both the type and the amount of carbs in each food. 

Table: Glycemic index vs  glycemic load of different foods.

However, recent studies have found that this blood sugar response, or glycemic impact, to each food is very individual and partly depends on your gut microbiome. So, the future of the Slow Carb Diet will rely on a continuous glucose monitor (CGM) to determine your unique responses to foods and lifestyle factors.

How To Do A Slow Carb Diet:

Step 1: Find Meals That Work For You With CGM And Microbiome Test

The slow carb diet aims to keep your blood sugar as steady as possible by focusing your meals around protein and carbohydrate foods that won’t spike your blood sugar. 

Microbiome tests will suggest foods that your gut bacteria love. Incorporate them into your meals and observe the blood sugar response.

Use a continuous glucose monitoring device, such as a Nutrisense or Dexcom, and journal your food for at least a week with your typical meals. Also, write down your hunger levels and blood sugar response the next morning. 

If certain foods or meals spike your blood sugar or result in extremely low blood sugar within a few hours after, then they don’t work for you. You shouldn’t be eating them on a regular basis. Keep eating meals and food items that stabilize your blood sugar. 

Step 2: Find Your Individual Low Glycemic Impact Carbs

What we often find is that some people maintain blood sugar better with high-glycemic impact carbs, such as rice and potatoes. You may want to test starchy foods individually to find out your personal responses to each of these. In real life, however, you’d almost always mix starchy foods with fat, fiber and protein, so the actual impact on your blood sugar won’t be as high. 

Step 3: Plan Your Calorie And Meal Breakdowns Based On Your Goals

On a Slow Carb Diet, protein is still the king macro to focus on. Aim for 35%-50% of your calories from proteins, 30-35% from carbohydrates and the rest from fats. Some people may do better with less carbs and more fats, but you can’t do high-carb and high-fat. You have to choose one dominant energy source and stick with it. 

If you’re working to lose body fat, you have to be in a caloric deficit. To maintain weight, simply stay at maintenance calories.  If you want to lose fat, aim for a 500 calorie daily average deficit.

If you’re trying to gain muscles, you should be at least 500 calories surplus. Some people may find better results with hypertrophy if they add a fast carb and protein around their training sessions.

Once you know how many calories you’ll be eating, divide it by the number of meals, which could be 3-5 per day, unless you are doing intermittent fasting. 


The Low Glycemic Impact diet, or the Slow Carb diet, focuses on eating food that minimizes the impact on blood sugar. On this diet, you would eat more protein and fibers, and less processed carbs. This combination tends to increase the thermic effect of food and decreases net calories. The end effects are not just better blood sugar and fat loss, but also improved overall health.

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