Question 1

How many grams of carbs should I eat per day?

Accepted Answer

General recommendations: for a balanced diet (45-65% of calories from carbs), a 2,000 kcal/day diet requires 225-325 g carbs per day. For low-carb diets, 100-150 g/day is common. For ketogenic diets, under 50 g/day (often 20-30 g net carbs). For endurance athletes, 5-10 g per kg of body weight on training days. The minimum for brain function is 130 g/day per the National Academies Dietary Reference Intakes.

Question 2

What are carbohydrates and what types exist?

Accepted Answer

Carbohydrates are macronutrients composed of carbon, hydrogen, and oxygen, providing 4 kcal per gram. Types: simple carbohydrates (sugars) include monosaccharides (glucose, fructose, galactose) and disaccharides (sucrose, lactose, maltose), absorbed quickly. Complex carbohydrates include starch (long glucose chains, absorbed more slowly) and dietary fibre (indigestible plant cell wall components that feed gut bacteria and slow glucose absorption). Whole foods contain complex carbs and fibre; refined foods are primarily simple carbs.

Question 3

What percentage of calories should come from carbs?

Accepted Answer

The Dietary Guidelines for Americans recommend 45-65% of total calories from carbohydrates for the general adult population. For a 2,000 kcal diet, this means 900-1,300 kcal (225-325 g) per day. Athletes performing high-intensity endurance exercise may need higher percentages (60-70%). Low-carb diets target 10-30% of calories; ketogenic diets target under 5-10% (under 50 g/day). Individual needs vary based on health goals, metabolic health, and activity level.

Question 4

What are net carbs and when should I count them?

Accepted Answer

Net carbs = total carbohydrates - dietary fibre - sugar alcohols (partially). Since fibre is not digested and does not significantly raise blood glucose, net carbs better approximate the glycaemic impact of a food. Net carbs are used in keto and low-carb diets. For standard calorie counting and diabetes management using exchange lists, total carbohydrates (as labelled) is the standard metric. Erythritol has minimal impact on blood sugar; other sugar alcohols (maltitol, sorbitol) have partial glycaemic impact.

Question 5

What foods are high in carbohydrates?

Accepted Answer

High-carb foods: grains and starches (bread, rice, pasta, oats, 45-80 g carbs per 100 g dry), potatoes and starchy vegetables (17-22 g per 100 g), legumes (beans, lentils: 20-60 g per 100 g dry), fruits (10-25 g per 100 g), dairy (lactose: ~5 g per 100 g milk), sugar and sweets (80-100 g per 100 g). Low-carb foods: non-starchy vegetables (<5 g per 100 g), meat, fish, eggs, oils, and cheese (0-1 g per 100 g).

Question 6

Do carbohydrates cause weight gain?

Accepted Answer

Carbohydrates do not directly cause weight gain; excess calorie intake (from any macronutrient) causes weight gain. Carbs are stored as glycogen in liver and muscle (limited to about 400-500 g total). Excess carbohydrates beyond glycogen storage are converted to fat via de novo lipogenesis, but this is an inefficient process. High-carb foods are often calorically dense and hyperpalatable, which can contribute to overconsumption. Controlled trials show similar weight loss on low-fat vs. low-carb diets when calories are matched.

Question 7

How does carbohydrate intake affect blood sugar?

Accepted Answer

Carbohydrates are broken down to glucose and absorbed into the bloodstream, raising blood sugar (glucose). The glycaemic index (GI) and glycaemic load (GL) measure how quickly and how much a food raises blood glucose. High-GI foods (white bread, sugary drinks) cause rapid blood sugar spikes; low-GI foods (legumes, whole grains) produce slower, more sustained blood sugar rises. Pairing carbs with protein, fat, and fibre slows glucose absorption.

Question 8

What happens if I eat too few carbs?

Accepted Answer

With very low carb intake (under 50 g/day), the body depletes liver glycogen within 24-48 hours and enters ketosis, producing ketone bodies from fat as an alternative fuel. This causes the "keto flu" in the first 1-2 weeks: fatigue, headache, irritability, and brain fog as the brain adapts to using ketones. Long-term, very low carb intake can reduce athletic performance in high-intensity activities (which rely on glycogen), and may affect mood and hormonal function in some individuals.

Question 9

Should endurance athletes eat more carbohydrates?

Accepted Answer

Yes. Carbohydrates are the primary fuel for high-intensity exercise and are stored as glycogen in muscles and liver. Endurance athletes are typically recommended 5-7 g carbs per kg body weight on moderate training days and 8-12 g/kg on high-volume training days. Carbohydrate loading (eating 8-12 g/kg for 2-3 days before a marathon) maximises glycogen stores and can improve performance in events lasting more than 90 minutes.

Question 10

What is the difference between refined and unrefined carbohydrates?

Accepted Answer

Refined carbohydrates have been processed to remove the bran and germ (e.g., white flour, white rice, added sugars). This removes most fibre, vitamins, and minerals, leaving primarily starch and sugar. Unrefined (whole) carbohydrates retain the bran and germ (e.g., whole wheat flour, brown rice, oats, legumes). Unrefined carbs digest more slowly, cause lower blood sugar spikes, provide more fibre, and have a better nutrient profile. Dietary guidelines broadly recommend minimising refined carbs.

Diet type	Carb range	Fits?
Standard (45-65%)	45-65%	Yes
Low-carb (20-45%)	20-45%	No
Very low-carb / Keto (<20%)	5-20%	No
High-carb / Endurance (60-70%)	60-70%	No

Diet	Carb % Range	For 2,000 cal	Primary purpose
Standard	45-65%	225-325g	General health
Low-carb	20-45%	100-225g	Blood sugar, weight loss
Ketogenic	5-10%	25-50g	Ketosis, epilepsy
Endurance athlete	55-70%	275-350g	Glycogen replenishment

Diet type	Carb range	Fits?
Standard (45-65%)	45-65%	Yes
Low-carb (20-45%)	20-45%	No
Very low-carb / Keto (<20%)	5-20%	No
High-carb / Endurance (60-70%)	60-70%	No

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