Zero-Carb Diet and Workouts: A Good Match or Recipe for Disaster?

Thinking of going carb-free while working out? Find out why it might not be the best idea for strength and stamina.

Highlights:

Carbs are essential for sustaining workout energy and performance
A zero-carb diet can lead to fatigue, electrolyte imbalances, and poor recovery
A balanced diet with complex carbs supports long-term health and fitness

Carbohydrates have long been a controversial subject in the fitness and nutrition world. Some swear by low-carb or keto diets for weight loss and mental clarity, while others argue that cutting out carbs entirely can backfire, especially when it comes to athletic performance. Nutrition consultant Justin Gichaba recently shared his personal experience with a seven-day carb-free diet, revealing both its benefits and its drawbacks- particularly in the context of working out. This raises an important question: is it a good idea to eliminate carbs from your diet when you work out regularly?

Carbohydrates and Weight Loss
Different diets emphasise different levels of carbohydrate restriction. And some diets claim carbohydrate to be the villain of their weight loss program.

‘Did you know?
Carbohydrates are the body's preferred fuel source during high-intensity workouts. Without them, your performance can drop by up to 30%! #fitnesstips #workoutfuel #carbfacts #healthyliving #balanceddiet #medindia’

Justin Gichaba’s Experience with a Carb-Free Diet

Justin Gichaba, a well-known nutrition consultant, experimented with a strict seven-day carb-free diet to see how it would affect his body, especially in terms of weight loss and energy levels. According to Gichaba, cutting out carbs initially made him feel lighter, less bloated, and mentally clearer. However, he quickly noticed a significant drop in his workout performance.

"I had less energy going into the workouts and I noticed a significant decrease in how well I lifted as well as my stamina during my harder cardio," Gichaba shared on Instagram.

Right Types of Carbohydrates
Eating the right carbohydrates is the golden secret to good health. Instead of a no-carb diet choose the right ones that rub the goodness of carbohydrates on your energy levels, appetite and mood.

What are Carbohydrates?

Carbohydrates serve as the body’s primary fuel source during physical activity (). When they are absent, the body is forced to rely on fat and protein for energy, which is less efficient for high-intensity exercise. Gichaba concluded that while low-carb diets might work for some people under specific circumstances, cutting out carbs entirely is unlikely to support optimal workout performance.

Carbohydrates and Its Role in Obesity
Over 1 billion people world-wide are obese thus affecting their health due to their nutrition and lifestyle. 3.9% of India’s population is obese! Know more about obesity and its prevention.

How Your Body Reacts to Zero-Carb Diets

According to Mitushi Ajmera, a senior master fitness trainer and nutritionist, a zero-carb diet triggers several physiological and metabolic changes in the body:

Glycogen Depletion

During the first 24 to 48 hours without carbs, the body depletes its glycogen stores- the sugar stored in the muscles and liver (). Since glycogen holds water (about 3 grams of water per 1 gram of glycogen), the initial weight loss is often due to water loss rather than fat loss.

Ketosis and Fat Burning

Once glycogen is exhausted, the body starts producing ketones as an alternative energy source, burning fat for energy instead of carbohydrates. This metabolic state is known as ketosis and is the foundation of the keto diet ().

Energy and Mood Swings

The transition to ketosis can cause side effects such as headaches, fatigue, dizziness, muscle cramps, and poor sleep (). Ajmera notes that this is due to electrolyte imbalances and the body adjusting to a new fuel source.

Appetite Suppression

Ketones naturally reduce hunger (). Ajmera mentions that some people end up eating less overall once they adapt to a low-carb diet.

Stabilized Blood Sugar and Insulin Levels

A zero-carb diet can stabilize blood sugar and reduce insulin spikes, which may benefit people with type 2 diabetes or insulin resistance ().

Digestive Issues

Since carbohydrates are a major source of fiber, cutting them out can lead to constipation and altered gut health.

Administering Carbohydrates and Omega-3 Fatty Acids Before & During Heart Surgery Reduces Later Complications
Administration of carbohydrate load before and ω-3 polyunsaturated fatty acid infusion during heart surgery reduces complications and hastens patient recovery.

Why a Zero-Carb Diet May Not Be Sustainable

Dr. Birali Swetha, chief dietician at Gleneagles Aware Hospital, Hyderabad, explains that while low-carb or ketogenic diets can help with weight loss and blood sugar control, a strict zero-carb diet can lead to nutrient deficiencies and long-term health risks.

"Fiber, vitamins, and minerals found in carbohydrate-rich foods are essential for digestion, gut health, and overall well-being," Dr. Birali said. A complete lack of carbs can cause electrolyte imbalances, constipation, and reduced microbial diversity in the gut, which can weaken immunity and digestion over time.

Moreover, long-term adherence to a zero-carb diet is challenging for most people. Dr. Birali recommends a balanced approach, where complex, fiber-rich carbs such as whole grains, fruits, and vegetables are included in the diet to support overall health.

Role of Carbs in Workout Performance

Carbohydrates play a critical role in fueling workouts, particularly high-intensity training like weightlifting, running, and cycling. Without adequate glycogen, the body struggles to sustain energy output, leading to reduced strength, stamina, and endurance ().

Gichaba advises that athletes and active individuals should aim for 25% to 30% of their daily calories to come from carbs (about 125–150 grams for a 2,000-calorie diet). This ensures the body has enough fuel for effective workouts while still maintaining the benefits of a controlled carb intake.

When it Comes to Carbs, Balance is the Key

While cutting carbs may offer short-term benefits such as quick weight loss and improved mental clarity, it is not a sustainable or effective strategy for individuals who work out regularly. Carbs are essential for workout performance, muscle recovery, and overall energy levels. A balanced approach that includes complex carbs, lean protein, and healthy fats is more likely to support long-term health and fitness goals.

References:

Carbohydrates as a source of energy - (https://pubmed.ncbi.nlm.nih.gov/8116550/)
Physiology, Fasting - (https://www.ncbi.nlm.nih.gov/books/NBK534877/)
Ketogenic Diet - (https://www.ncbi.nlm.nih.gov/books/NBK499830/)
Ketogenic Diets: Side Effects, Attitude, and Quality of Life - (https://pubmed.ncbi.nlm.nih.gov/35036220/)
Do ketogenic diets really suppress appetite? A systematic review and meta-analysis - (https://pubmed.ncbi.nlm.nih.gov/25402637/)
Effect of low carbohydrate diets on insulin resistance and the metabolic syndrome - (https://pubmed.ncbi.nlm.nih.gov/34468401/)
Glycogen availability and skeletal muscle adaptations with endurance and resistance exercise - (https://pubmed.ncbi.nlm.nih.gov/26697098/)

Source-Medindia