Eating bread can help you lose weight — as long as it’s high in fibre

For years bread was blamed for accumulating pounds, shunned as a carb unhelpful for your waistline. However, new evidence suggests that – provided you use your loaf and choose the right variety – bread is not only good for you, but will aid in weight loss. These welcome results come from a study recently published in the journal Clinical Nutrition. Swedish researchers from Chalmers University of Technology showed that replacing regular wheat with high-fiber bread and cereal led to weight and fat loss in a group of mostly middle-aged men and women.

Ricard Landberg, professor of food and health and lead author of the paper, asked half of the 242 overweight participants to eat a bowl of rye breakfast cereal, four to six slices of rye bread (think Ryvita) and 2-2.5 slices of rye bread soft wheat every day while others eat refined wheat varieties with the same total calorie intake. The main difference was that the rye group “got about 30 grams of fiber per day compared to only 8 grams that got the others,” says Landberg. His goal was to determine how the switch affected their ability to lose pounds.

After 12 weeks, during which participants were weighed and checked regularly, the results showed that the high-fiber group lost an average of one kilogram more than the refined wheat group, an amount entirely attributable to the additional fat loss. “Previous epidemiological studies have clearly shown that foods high in fiber are generally good for long-term weight control,” says Landberg. “But ours was the largest study that looked specifically at how high-fiber cereals in the diet affect body weight and body fat, and we’ve shown that fiber has an important and beneficial effect.”

There is a growing consumer demand for high-fiber bread. Research conducted by SuperValu in 2021 showed that sales of healthy bread options, including chia seed loaves, increased 20%, with 45% of respondents saying they buy bread once a week.

“It’s a myth that bread is bad for us and automatically leads to weight gain,” says Dublin-based dietitian and nutritionist Avin Bannon.

Regular bread is actually low in calories with only about 80 calories per slice, and if you choose a variety rich in fiber, such as wholegrain, rye, and seed bread, the higher fiber count brings many benefits for digestion and gut health.

Although it’s counterintuitive, it’s not an entirely new concept that high-fiber bread can help you shed tough weight. Ever since the release of Audrey Eaton’s F-Plan bestselling diet book in the ’80s, dieters have been engrossed in fibres. I remember the book was like a bible for my mom and her friends who used to fear low-fiber foods the way we now fear carbohydrates. Eaton advised readers to consume massive amounts of fiber for rapid and sustained weight loss. This approach achieved 5:2 dominance among aspiring dieters, and although the fiber trend was falling off the radar, our heads turned by a series of trendier dietary approaches, it’s now back and with broader scientific support.

How it works

How fiber works to blast body fat is interesting. Some fibers are known to increase in size and become gel-like in the stomach and promote feelings of fullness. The ‘satiation effect’ means that if we eat enough fiber, we are generally less inclined to snack and overeat as hunger pangs diminish.

“We also know that fiber traps some of the energy or calories we take in from food, especially fats, and makes them unavailable for absorption by the body,” says Landberg. “We have shown in some of our other studies that more fat from food is excreted when rye fiber is consumed.”

Then there’s how fiber nourishes our gut bacteria and works with the microbiome, the vast ecosystem of yeasts, bacteria, fungi and viruses that inhabit our digestive system.

“My message is to try to get as much fiber as possible in your diet,” says Professor John Cryan, from APC Microbiome Ireland at University College Cork. “The microbiome is a medium and requires fuel in the form of the food we eat – eating more whole grains and green vegetables is a great way to provide this essential fuel.”

Studies have shown how a low-fiber diet causes chronic inflammation in the gut that interferes with the way we digest food and use calories, causing our bodies to store more and more extra calories as fat.

In a research paper from the University of Gothenburg in Sweden, researchers studied the effects on rats switching their diet from a high-fiber to a typical low-fiber Western-style food. After just three to seven days of eating low-fiber foods, the mice developed gut problems.

After several weeks of eating low-fiber foods, their blood sugar levels rose, and they began shedding more body fat. It’s possible, the researchers said, that the effects are “translatable to humans.”

Increased fiber intake can stimulate gut bacteria to produce metabolites that affect how full we feel and boost metabolism. A high-fiber diet may suppress appetite by sending signals from the gut to the brain telling it that you feel full.

“We don’t have the full picture yet, but in our study we can see that some bacteria were largely present after the participants ate the high-fiber foods,” Landberg says. “These bacteria are known to produce short-chain fatty acids, such as butyrate, a molecule that signals an increased feeling of satiety.”

It’s confusing to think that we can avoid creeping weight gain by increasing our bread intake. Landberg says he does not intend to loosen his habit of snacking on rye bread. “So far, he hasn’t gained any weight, so I’ll keep working,” he says.

His advice is that we all find our own fiber fillers. “If everyone could increase their fiber intake, I’m sure it would have a beneficial effect on body weight.”

How do we know we are getting enough?

National guidelines recommend 24 to 35 grams of fiber per day to keep your digestive system working at its best. However, according to the Irish Nutrition and Dietetic Institute, nearly 80% of Irish adults do not eat enough fiber.

You can start by checking food labels and counting the number of fibers using the tracker.

Eat whole fruits and vegetables, not juices and soups

Eating large amounts of processed foods didn’t help our decreased intake, says Thomas Barber, associate professor and emeritus consultant in endocrinology at the University of Warwick, a leading researcher on the effects of fiber. But no food trends like grinding fruits and vegetables into smoothies and smoothies or blending soups until smooth are also unhelpful. They provide fiber to our bodies differently and less effectively than whole fruits or vegetables.

“Eating close to its natural state is the best way to get more fiber,” Barber says. “In general, this means minimal processed foods and whole fruits and vegetables.”

The more processed the food, the less likely it is to contain fiber

In a study of processed foods, researchers at the University of Otago found that not all foods made with fiber are created equal. Although whole grains are an important source of fibre, their benefits may be diminished when processed densely, according to Professor Jim Mann of the Department of Medicine and lead author on the paper.

Participants with type 2 diabetes were asked to eat more processed whole-grain foods such as oats and wholegrain bread for two weeks, and then eat more processed whole-grain foods such as instant oats and wholemeal bread for another two weeks. Results showed an improvement in blood sugar levels after meals and throughout the day when participants ate minimal processed whole grains.

“Whole-grain foods are now widely seen as beneficial, but increasingly some of the whole-grain products on supermarket shelves are ultra-processed,” says Professor Mann.

It also found that participants’ weight increased slightly after two weeks of eating processed whole grains and decreased slightly after eating minimally processed whole grains.

We are beginning to understand that when you grind whole grains you remove some of the benefits.

Don’t cut out carbohydrates completely

The trend towards avoiding carbohydrates has greatly affected our fiber intake.

“Many carbohydrate foods are high in fiber, so by cutting out things like bread and cereal, we’re missing out on a major source of them in our diets,” Barber says. “The key is to look for whole grain versions of these products and avoid the highly processed types.”

What is the best source of fiber?

Choose rye, spelt, buckwheat, or seeded breads and grains such as bulgur, spelt, pearl barley, quinoa, teff, buckwheat, brown rice, and oatmeal.

Fiber is part of plant foods that mostly pass through the stomach and small intestine without being digested. Fruit and vegetables are the obvious sources, but whole grains, cereals, oats, porridge, figs, nuts, seeds, peas, beans, and lentils are all good sources of fiber.

Best sources include:

  • Chia seeds 38g of fiber per 100g
  • Beans 6.8 grams
  • Canelli Bean 5.7 g
  • Cranberry 6.5 g
  • Avocado 5.9 g
  • 15.2 grams of dark rye bread
  • 7.7 g high bran bread
  • Multigrain bread 6.5 g
  • Whole grain 6.2g
  • Whole wheat bread 5.8 g
  • Flax seeds 27.3 g
  • Hazelnut 6.5 g
  • 6.3 grams peanuts
  • 5.6 grams almonds
  • Whole wheat pasta 4.5 g
  • black rice 2.8 g
  • Kidney beans 5.5 g
  • Chickpea 4.6 g
  • 3.7g cooked beans
  • Sweet peas 3.7 g
  • Carrots 2.7 g
  • 2.3 g broccoli
  • Cabbage 1.9 grams


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