The Ultimate Guide to Carbohydrates

The ultimate evidence based guide to carbohydrates for health, sports performance and weight loss.
The ultimate evidence based guide to carbohydrates for health, sports performance and weight loss.

Carbohydrates are polarising. Some people believe carbs are bad; the reason for all their body weight woes and health issues. Whereas other champion carbohydrates for being heart healthy and performance enhancing. These contradictory viewpoints, makes it hard for many of to decipher whether carbs are the devil or our best friend.

If you are looking for clarity on carbohydrates for health, sports performance and weight loss than this article is for you. This guide to carbohydrates discusses the most common questions with explanations that are back by science so that you can make informed decision about your diet.

What are carbohydrates?

Carbohydrates (or carbs) are one of three macronutrient we need in our diets in large amounts, alongside protein and dietary fats. Unlike the other macronutrients, there is no minimum dietary requirement for carbohydrates however carbohydrates can contain essential micronutrients our bodies need.  Carbohydrates are the body’s main source of energy, fuelling processes in the body. Each gram of carbs contains 4 calories.

All carbohydrates are made up of sugar molecules. Sugar molecules linked together in chains to form starches or fibre. Carbohydrates can be categorised into two different groups – simple carbohydrates & complex carbohydrates.

When we eat carbs, they are broken down by the body into glucose, which can be used right away for energy or stored away to be used later. When sugar level increases in the body, a hormone called insulin is released by the pancreas. Insulin moves glucose from the blood to the cells where it can be used for energy. Although some carbs like simple sugars make blood sugar levels rise faster than others.

Simple Carbohydrates

Selection of Simple Carbohydrates

Simple carbohydrates consist of just one or two molecules of sugar therefore are quickly broken down by the body supplying a short energy boost. They are naturally found in foods like fruit, non-starchy vegetables, milk but also they are also found in refined and processed food.

Example of simple carbohydrate:

  • Fruits: bananas, oranges, apples and berries
  • Non-starchy vegetables: pepper, tomatoes, mushrooms and leafy green vegetables
  • Dairy products
  • Sweets, candy and chocolate
  • Sugar, honey and syrups
  • Juices and soft drinks

Complex Carbohydrates

Selection of complex carbohydrate

Starches and fibre are complex carbohydrates. These both contain longer chains of sugar molecules than simple carbs. Therefore, they take longer to break down, providing the body with a more sustained long-lasting energy than simple carbs. Fibre is plant carbohydrate which cannot be digested by human bodies but feed the gut microbiome and colon. Fibre helps with bowel movement and reducing total cholesterol.Starches and fibre can be found in the same in the food however some foods are high in starch than fibre.

Examples of complex carbohydrates:

  • Grains such as rice, oats, quinoa and barley
  • Potatoes and root vegetables
  • Breads, pasta and flour
  • Nuts, seeds and pulses

What are the benefits of eating carbs?

Enhancing athletic performance

Eating carbohydrates will improve athletic performance by providing the body with energy; allowing you to perform for longer and delaying fatigue. This is because the body stores carbs for energy in the muscle and liver as glycogen, however the capacity of these stores is limited. When you perform exercise or high intensity activities, more glycogen gets used up which causes a higher demand on carbohydrates. Studies have shown that aerobic endurance is directly related to initial muscle glycogen stores and that depleted stores are correlated to increased perception of fatigue.

Improving exercise recovery

In order to train or compete on a consistent basis, we have to ensure our bodies adequately recovered from previous physical activity. Post-exercise carbohydrate ingestion improves exercise recovery by increasing glycogen resynthesis which becomes diminished after training.

Supporting the immune system

Carbohydrates provide us with key micronutrients such as polyphenols which can improve immunity. High intensity exercise workloads and competitive athletic events (i.e. long endurance events, CrossFit games style events) can stress us not only physiologically but metabolically, mentally and emotionally. This type of stress is linked to immune dysfunction, inflammation, oxidative stress, and muscle damage. Numerous studies have shown an increased risk of illness with prolonged, intensive exercise. Therefore it’s beneficial to consume a well-balance diet including healthy carbs and polyphenols (fruit, vegetables, grains) which can reduce inflammation from exercise and improve viral protection.

Some carbs are good for your heart

Whole grains are protective for the heart. Studies have found that eating whole grains are associated with a reduction in total cholesterol and risk of coronary heart disease. However refined carbohydrates particularly added sugars and sugar-sweetened beverages increase risk factors for heart disease.

How much carbs should I be eating?

The number of calories and subsequently carbs you need is dependent on a number of factors, such as your weight, body composition, goals and training amount & style. However, with regards to setting up your total calorie and macronutrient goals, it is key to prioritise protein intake (more on protein here). After you’ve figure out the amount calories then protein you need, you can essentially split the remainder of calories between carbs & dietary fat (ensuring you have a minimum of 20% of calories coming from dietary fat).

When should I eat carbohydrates?

For training & workouts

Previously there was an emphasis on eating carbs and protein post-workout within the anabolic window, thought to be 30-60 minutes after you finish your workout. However more recent findings have shown that total daily protein and carb intakes are more important than nutrient timing for the average individual.

On the other hand, post workout carbs and protein may be beneficial if you train fasted (i.e. before you’ve eaten breakfast). Or if your last meal was more than 3-4 hours ago, then pre- or post-workout ingestion of protein and carbs will also be beneficial.

No carbs after 5/7/10pm???

A common belief regarding carbohydrates is that shouldn’t eat them in the evening or at night for weight loss. Currently research is contradictory whether it’s better to eat more calories and carbs at any particular time in the day.

My personal recommendation when it comes to nutrient and meal timing is do you – what you eat and how much you eat is far more important than when you eat. Focus on eating more good quality foods first and tailor the timing to what feels good and fits with your lifestyle.


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What kind of carbs should I be eating?

When it comes to carb intake both quantity and quality matters. It’s a common belief that complex carbohydrates are better than simple carbs (or sugars) however this is an over simplified view. The best indicators of the quality of a carbohydrate is the amount and type of fibre, the level of processing, and to some extent glycaemic index and glycaemic load. With that being said, the best types of carbs to eat are sources which are whole, nutrient rich and contain fibre. Try to eat more whole food carbohydrates or carbohydrates in a form that is closest to its natural state. For example:

  • Whole fruits contain dietary fibre and more vitamins than their fruit juice counterpart. Fruit juices contain more calories and are less satisfying than whole fruit. Additionally, drinking fruit juice causes a greater spike in blood sugar than eating the whole fruit.
  • Whole grains contain more dietary fibre and micronutrient than refined grains foods. However some refined foods are enriched or fortified with micronutrients.

Examples of minimally processed, nutrient dense, fibre-rich foods

  • Fruits: bananas, oranges, apples, pears, berries, melon, kiwi etc
  • Non-Starchy Vegetables: leafy greens, salad greens, broccoli, carrots, cucumber, mushrooms, peppers, tomato etc
  • Starchy Vegetables: potato varieties, yam, corn, peas, butternut squash, parsnips
  • Pulses: black beans, chickpeas, kidney beans, black eyed peas, lentils, lima, marrowfat, etc
  • Whole Grains: wild rice, millet, amaranth, quinoa, bulgur wheat, steel cut oats, popcorn, etc
  • Nuts & Seeds: chestnuts, cashews, pistachios, pumpkin seeds, sunflower seeds, sesame seeds

Examples of moderately processed and nutritious foods

  • Wholemeal or whole wheat (rye, spelt, buckwheat) flours and flour-based products:
    • Breads
    • Pasta
  • Brown rice
  • Rolled oats, oat bran and unsweetened instant oats
  • Unsweetened breakfast cereals: granola, muesli, bran flakes, shredded whole wheat etc

Examples of refined grains

The following foods are considered highly refined grain foods which are rich in starch but due to the refining process all or most of the natural dietary fibre and nutrients are removed. It is important to note some refined grain foods are enriched or fortified with nutrients. These can be an okay source of carbohydrates when eaten as part of a balanced diet however we should strive to less processed carbs where possible for the added health benefits.

  • White flour and flour based products:
    • Fortified breads
    • Pasta
  • White Rice
  • Unsweetened refined fortified cereals: puffed grains, corn flakes

What kind of carbs should I be limiting?

Added Sugars & “Free Sugars”

Sugars that are added to food whilst processing, manufacturing or preparing food are known as added sugars. Free sugar refers to sugars naturally present in honey, syrups and unsweetened fruit juices as well as added sugars. Studies have found decreased consumption of added and free sugar are associated with weight loss whilst increases consumption is associated with weight gain. Furthermore, research has found that higher intakes of free sugars is related increased total cholesterol levels, blood pressure and other risk factors for heart disease. Free sugars also contribute to tooth decay and dental disease. The World Health Organisation (WHO) recommends reducing free sugar intakes below 5-10% of total calorie intake.

Examples of free sugars:

  • Table sugar (all types brown, white, icing)
  • Coconut sugar
  • Honey
  • Syrup; maple, golden, agave, corn syrup
  • Molasses or treacle
  • Fruit juice

Highly Refined Empty Carbohydrate Foods

This final group of food consist of foods that make you smile and drool just thinking about them. They are deliciously tasty and hyper palatable which is why we tend to love them so much. However, they are also very likely to be highly refined, empty of nutrients, high in calories and quite addictive. It’s fine to eat these foods as an occasional treat however it best not to regularly eat these foods.

Examples of highly refined empty carbohydrate:

  • Sugar-sweetened beverages; sodas, squash, coffee drinks smoothies and milkshakes
  • Ice cream and desserts
  • Cakes, biscuit and cookies
  • Sweets, candy and chocolate
  • Sweetened breakfast cereals
  • Pasta sauces
  • Flavoured yoghurts

Is it necessary to consume carbohydrates?

No as there is no minimum dietary requirement of carbohydrates. Although, carbohydrates are the bodies main source of energy, when carbs are scarce your body will use dietary fat or protein for energy instead. With that being said healthy carbs such as fruit, vegetables, pulses and whole grains are great sources of fibre, vitamins and minerals. Without these sources of micronutrients, we can put ourselves at of risk deficiencies which can make us vulnerable to illness.

It’s easy to see why many people reduce or avoid eating carbs all together. Carbs have been heavily vilified in the media in general. Our favourite junk food items are typically highly processed and carb heavy. But remember not all carbs are created equal therefore we cannot paint them with the same brush.

Do low carb & keto diets work for weight loss?

Restricting carbohydrates is often used as a method to lose weight or reduce body fat. Whilst low-carb approaches to dieting can definitely lead to weight loss in the short term, by reducing caloric intake. The jury is still out whether low-carb diets work in the long-term, as some argue that these diets can be very difficult to maintain. Restricting carbs can considerably decrease variety of food choices and make it hard to eat out.

I believe adherence, sustainability and success of low-carb diets is dependent on your lifestyle, personality, preference and preparedness. Low-carb diets aren’t for everyone however they’re simple to follow approach to weight loss which some people may benefit from. However, I would like to emphatically state that for most people, when eaten maintaining a caloric deficit as part as a healthy balanced diet, carbs do not get in the way of fat loss.

Do low carb & keto diets affect exercise performance?

Low carb & keto diets may negatively affect exercise performance which may be a disadvantage if you have if you have specific training or strength goals. Carbs are the bodies preferred energy and whilst fat can be used for fuel it’s not as quickly available when training at high intensities.

“the depletion of glycogen levels is a limiting factor of performance during sessions in which high exercise intensities are required; therefore ensuring a high carbohydrate availability before and during exercise is of major importance. A high carbohydrate availability has also been positively related to the exercise-induced adaptations to resistance training…”

Carbohydrate Availability and Physical Performance: Physiological Overview and Practical Recommendations, Mata et al, 2019.

Essentially low carb and keto diets can deplete muscle glycogen, leading to fatigue. Research even indicates that muscle fatigue increases in almost direct proportion to the rate of depletion of muscle glycogen.


Nayomi Pennant
I’m an utter foodie who is passionate about wellbeing, health & fitness. I created Her Food and Fitness to share delicious nutritious recipes & feasible fun fitness advice for women. My mission is to provide women with food and fitness advice on how to lose fat, build lean muscle and stay healthy.