Carbohydrates: all you need to know

Let’s talk carbs (carbohydrates). Because I think they get a bad rep. Especially thanks to the Atkins diet or sayings like ‘no carbs before marbs’ *insert angry face emoji here*.The issue is not all carbs are created the same. Just like fats you have different types of carbs, and those carbs have different effects on your body.

Carbohydrates form one part of the three macronutrient groups; carbohydrates, proteins and fats (check out my blog about fats here). We need all three of these food groups in our diet to be healthy, and yep, that includes carbs.

Function of carbohydrates

1. Energy : The main function of carbohydrates is to provide us with energy. Carbohydrates are broken down into sugar and absorbed into the blood stream as glucose – the source of energy for cells (thanks to the help of insulin). Without enough energy (provided by carbohydrates) you will see a depletion in performance, be it sport performance or work performance (the human brain is about 2% of total body weight but accounts for about 20% of the body’s energy use – calories₁).

2. Fibre : carbohydrates also provide us with fibre. Not the kind you’d see advertised on the cereal box but the kind found in real food such as vegetables, fruits, legumes and grains. The fibre we find in whole food sources of carbs help support gut health and help us manage our weight and reduce cholesterol₂.

So if you feel tired when you’re working out, or your brain feels a bit cloudy, or maybe you’re even experiencing a low sex drive, you might need to just eat some carbs.

So why do you see people loose ‘weight’ when they cut the carbs?

Take a look at the word : carbohydrate. Take another look : carboHYDRATE. It’s actually in the name. For every gram of carbohydrate consumed the body retains around 3 grams of water₃. So when people cut carbs and see quick weight loss – they’re not loosing fat, they’re just loosing water weight. As soon as that person starts eating carbs again the water weight will come straight back on. This retention of water with carbs also helps explain some reasons for bloating, why you feel ‘slimmer’ in the mornings, or why you may have ‘put on weight in the last week’. Ladies – be especially careful of this as your hormones can affect this too (hello period bloat).

NOTE : any short term fluctuations in weight are not fat. Unless you have dramatically reduced your calorie intake (we’re talking towards starvation levels here) then you won’t be loosing fat in short periods of time. Personally I’m not a fan of the scales for fat / weight loss, but maybe more on that another time.

Types of carbohydrates

There are two main categories for carbohydrates; simple and complex. These terms refer to the chemical structure of the molecules that make up the food₂.

1. Simple carbohydrates: are broken down quickly and provide a quick burst of energy when consumed. Examples include:

  • Glucose
  • Sugar (sucrose)
  • Fruit & honey (fructose)
  • Malt sugar (maltose)
  • Dairy (lactose)

2. Complex carbohydrates: are larger compounds that require more time to be broken down, slowing digestion and absorption and preventing extreme changes in our blood glucose levels₂. Complex carbs include starches and fibre, which help manage weight and support cardiovascular disease. Examples include:

  • Whole grains (brown rice, oats, whole wheat, barley, quinoa etc.)
  • Beans / legumes
  • Vegetables, including starchy vegetables such as potatoes.

So what carbohydrates should you eat?

As with pretty much anything in nutrition always opt for the whole food option. We can’t say simple carbohydrates are better than complex carbohydrates and visa versa. Each have their own health benefits Let’s take fruit as an example. As a source of simple carbohydrates, fruit naturally contains sugar, but it is also a good source of fibre (unlike most processed foods with added sweeteners). Because of this, fruit doesn’t cause as sharp of a spike in blood glucose levels. In addition, fruit offers much more than just energy – it’s also a source of antioxidants, vitamins, and minerals₂.

So as a general rule of thumb stay away from the processed foods/carbs when you canif it looks like it does growing in the wild, it’s good. Also, to help get the full range of benefits from carbs eat a range of whole food carbohydrates. That being said, don’t be too strict with yourself. I LOVE bread, pasta & pizza. I ain’t giving them up anytime soon. Food is there to be enjoyed, so focus on nutrient-rich when you can, and enjoy the ‘less-nutritious’ foods as you want.

As always, let me know in the comments if you have any questions or thoughts!

Love Emma x


  1. PNAS, 2002, M.E. Raichle & D.A. Gusnard, Appraising the brain’s energy budget,
  2. Institute of Integrative Nutrition, 2020, Macronutrients 101 : Carbohydrates
  3. PubMed, 1992, S.N. Kreitzman, A.Y. Coxon, K.F. Szaz, Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition,

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