Fibre and why lifters under-eat it

Why lifters specifically get this wrong

Fibre is the least glamorous topic in nutrition and one of the highest-return. The reason lifters under-eat it is structural rather than careless: a diet optimised for protein and easy digestion tends to be low in fibre almost by construction.

• Protein sources contain no fibre. Chicken, fish, eggs, whey, beef — zero. The more of your plate is protein, the less is fibre-bearing.
• The default carbohydrates are refined. White rice, white pasta, bagels and rice cakes are chosen for convenience and easy digestion, and they are low in fibre.
• Pre-workout advice pushes fibre down. "Keep fibre low before training" is sound for comfort, and it becomes a whole-day habit.
• Fibre is filling, which feels like a problem in a surplus. People bulking deliberately avoid it to fit the calories in.
• Shakes and bars replace meals. Convenient, and usually low in fibre.

The result is a diet that looks careful on a macro tracker and is missing something the tracker may not even display.

What fibre actually does

• Satiety. The most immediately useful effect for anyone dieting. Fibre-rich foods have more volume per calorie and slow gastric emptying.
• Digestive regularity. The complaint people notice. High-protein, low-fibre diets are a common cause of constipation.
• Blood glucose. Soluble fibre slows carbohydrate absorption, flattening the response to a meal.
• Cholesterol. Soluble fibre lowers LDL modestly and reliably.
• Gut bacteria. Fermentable fibre is what the gut microbiome eats. This is the mechanism behind much of the long-term health association.
• Long-term disease risk. Higher fibre intake is one of the more consistent associations in nutritional epidemiology, linked to lower cardiovascular disease, type 2 diabetes and colorectal cancer risk.

How to actually get 30 g

Useful reference points, because most people have no idea what a gram of fibre looks like:

The practical moves, in order of how little effort they require:

1. Swap refined carbohydrates for their whole versions. Wholemeal bread, brown rice or mixed grains, potatoes with the skin. Adds 8–12 g a day with no other change.
2. Add a legume to one meal a day. Beans or lentils alongside the protein, or partly replacing the rice. 10–12 g in one move, and it adds protein too.
3. Make one snack fruit or nuts. 4–6 g.
4. Add vegetables to two meals. Not a garnish — a real portion. 6–10 g.
5. A tablespoon of chia or ground flax into yoghurt or oats. 5–9 g.

Any two of those gets most people from 15 g to 30 g.

Doing it without ruining your training

The legitimate concern is comfort — bloating, gas, and needing the toilet mid-session. All of it is manageable.

• Increase gradually. 5 g a week, not 15 g overnight. Almost all the discomfort people attribute to fibre comes from adding it too fast.
• Drink more water. Fibre without fluid is the specific recipe for feeling worse.
• Keep fibre low in the meal before training. Not in the whole day — shift it to meals further from your session.
• Cooked vegetables are easier than raw for most people.
• Some sources are gentler. Oats, peeled fruit and cooked carrots tend to be better tolerated than large volumes of raw brassicas or beans.
• Persistent symptoms are worth investigating — IBS and other conditions genuinely change what tolerable looks like, and a low-FODMAP approach may be relevant. That is a conversation with a dietitian, not a reason to eat 10 g a day.

Fibre while bulking or cutting

In a deficit

Fibre is your ally. High-volume, high-fibre foods let you eat more physical food for the same calories, which is most of what makes a deficit bearable. Aim for the upper end, 30–40 g.

In a surplus

Fibre works against you — you need to fit calories in, and fibre fills you up. The sensible compromise is to hit 25–30 g and get the remaining calories from more energy-dense foods rather than dropping fibre to fit them. See eating for muscle gain without excess fat.

If appetite is your limiting factor

Then fibre is genuinely part of the problem, and a lower-fibre approach around 20–25 g is a reasonable trade — see eating enough when you have no appetite.

Common questions

Do fibre supplements count?

Psyllium and inulin help with regularity and are better than nothing. They do not replace the other benefits of whole foods, which come bundled with micronutrients.

Does fibre reduce calories absorbed?

Slightly — very high fibre intakes reduce net absorption a little. Not enough to plan around.

Is too much fibre possible?

Above roughly 50–60 g a day some people get discomfort and reduced mineral absorption. Rare as a problem.

Do fibre grams count in my carbohydrate total?

In the UK and EU, labelled carbohydrate excludes fibre. In the US it is included, which is where "net carbs" comes from.

Will fibre make me look bloated?

Temporarily, if you increase it quickly. It settles within a week or two.

Is fruit sugar a problem?

No. Fruit is one of the easiest fibre sources and the sugar arrives with fibre and water. See fat loss myths that will not die.

The practical version

• Target 25–35 g a day, or about 14 g per 1,000 calories.
• Most adults get 15–20 g; protein-focused lifters often get less.
• Swap refined carbohydrates for whole versions and add a legume to one meal a day.
• Increase by about 5 g a week and drink more water to avoid discomfort.
• Keep fibre low in the pre-training meal, not across the whole day.
• Go higher in a deficit for satiety; ease off if appetite limits a surplus.