You love bread, but you also love fitting into skinny jeans, which is a common dilemma. Bad news: Bread isn't the best food for weight loss, especially white bread.
So what about sourdough? It's nutritionally similar to other breads, but it's fermented with healthy bacteria that allegedly can aid weight loss. Unfortunately, baking destroys these bacteria and makes sourdough just like any other bread.
Sourdough bread made with whole-grain flour is better for you than sourdough made with white flour. Like other whole-grain bread, it's the healthiest bread for weight loss.
What Is Sourdough?
It has a soft interior, chewy exterior and a slight tang that makes your sandwich that much more exciting. What is it about sourdough that makes it so unique and makes you wish for a bread diet? It's the type of yeast and the fermentation process.
According to Modernist Cuisine, sourdough is made from a special yeast called a starter, or levain, which is a mixture of flour and water that is fermented by lactic acid bacteria and wild yeast. Most of the bacteria in a starter are Lactobacillus, the same bacteria found in yogurt and other fermented foods.
Benefits of Fermented Foods
Humans have been fermenting foods for millennia. Originally a means of food preservation, fermented foods have more recently been studied for their health benefits.
Improved gut health is the major benefit for which fermented foods are touted. Often called the "gut microbiome," this collection of trillions of microscopic organisms living in the gastrointestinal tract are best thought of as a "virtual organ of the body," according to a 2018 article in the British Journal of Medicine.
Fermented Foods and Weight Loss
The fermentation process aids the creation of special substrates called short-chain fatty acids, or SCFAs. These SCFAs, butyrate, propionate, and acetate, play roles in energy metabolism, lipolysis (fat metabolism) and appetite control.
Interacting with the gut fatty acid reactors, propionate regulates satiety signaling. These signals are transmitted to the central nervous system where they create sensations of fullness and satiety. This plays a major role in appetite control and the regulation of energy intake. Acetate and butyrate also play roles in gut hormone production and appetite control.
According to the BMJ, research shows that increased production of SCFAs in the gut correlates with a reduction in diet-induced obesity. A 2018 systematic review and meta-analysis in Genes examined studies on the effects of prebiotics, probiotics and synbiotics (the healthy bacteria in fermented foods) and found that these dietary agents lead to significant reduction of weight and fat mass and body mass index, or BMI.
Bacteria in Sourdough Bread
How does sourdough stack up as a source of these powerful substances? Well, if you ate the dough raw, it would be pretty good. But that isn't very appetizing.
Unfortunately for sourdough lovers who want to lose weight, baking destroys these microbes, explains Carrie Dennett, MPH, RDN, CD. Sourdough bread is baked at 425 degrees Fahrenheit for 25 to 30 minutes. At that temperature and for that amount of time, you can expect the healthy bacteria to perish in the process.
Other types of processing, including alternate types of heat application, pasteurization and filtering, also destroy the helpful bacteria.
Sourdough Is Still Bread
With the major thing that sets it apart from other breads destroyed, sourdough is just like any other bread. And just like any bread, its relative "benefits" for weight loss depend on the type of flour it's made with. White, wheat, whole wheat and rye are a few types commonly used to make sourdough.
All of these are high in carbohydrates, which can make or break your diet, depending on the type.
Carbohydrates and Blood Sugar
One of the main reasons carbs are maligned when it comes to weight loss is their effect on blood glucose. Some carbs can sharply raise glucose, leading to fluctuations in blood sugar that have effects on appetite, energy and mood, according to Joy Bauer, MS, RDN.
These types of carbs are called simple carbs. They are simple in structure, and they are broken down easily to glucose and absorbed into the bloodstream all at once. Eating a lot of foods with simple carbs can lead to unhealthy weight gain and metabolic syndrome, according to a 2018 article in the International Journal of Environmental Research and Public Health.
Complex carbohydrates, on the other hand, have more complex structures. This causes them to be broken down more slowly, and they release a more steady supply of glucose into the bloodstream.
Effects of Different Flours on Blood Sugar
This distinction results from the different methods for processing flours. White flours are made from whole grains; however, they have been milled to give them a finer texture. This milling process strips the grain of its bran and germ, which are the components of grain that contain most of the beneficial nutrients.
With whole-wheat flour, as its name implies, the bran and germ are not removed, and the flour retains its nutrients.
Fiber and Weight Loss
Dietary fiber, the part of plant foods that passes through your body mostly undigested, plays a major role in health and weight management. Fiber adds bulk to your diet without calories; eating a meal rich in fiber is likely to make you feel full more quickly than one low in fiber.
Foods that contain a lot of fiber, such as crunchy vegetables, also have low calorie density. Eating more fiber helps you stick to a calorie-reduced diet without feeling unsatisfied.
But even in the absence of calorie restriction, eating more fiber can help you lose weight. In a 2018 study in Nutrition, 15 obese adults were counseled to increase their fiber intake to 35 grams daily. They also increased their protein intake. These two changes resulted in statistically significant reduction in calorie intake and weight during the 12-week trial.
White vs. Whole-Wheat Sourdough
Whole-wheat flour is also lower in calories and higher in protein, which is another nutrient that increases satiety and can help control appetite and calorie intake.
Healthiest Breads for Weight Loss
The thing about bread is that, no matter how you slice it, it's not as good for weight loss as other foods. Even whole-grain sourdough is processed when it's ground down to flour. Physical changes alter a food's digestibility, according to the Glycemic Index Foundation; flour, whether white or whole grain, is still digested more quickly than a grain eaten intact.
For example, whole long-grain brown rice takes your body longer to digest than a piece of whole-wheat sourdough because your body has to do more of the work to break it down and digest it.
This is minutiae, though, in the grand scheme of things. The fact is that weight loss is primarily about calorie control. If you can eat sourdough and still create a calorie deficit by staying below your body's daily energy needs, you can lose weight. But if the effects of bread on appetite control and blood sugar affect you as they do many people, you'll find it's easier to exceed your calorie goals and gain weight.
- Modernist Cuisine: Sourdough Science
- Tufts: Fabulous Fermented Foods
- British Journal of Medicine: Role of the Gut Microbiota in Nutrition and Health
- Genes: Dietary Alteration of the Gut Microbiome and Its Impact on Weight and Fat Mass: A Systematic Review and Meta-Analysis
- Today's Dietitian: The Facts About Fermented Foods
- King Arthur Flour: Classic Sourdough Bread: Time Steps in for Added Yeast
- Joy Bauer: Refined Grains: How Food Affects Health
- MedlinePlus: Simple Carbohydrates
- MedlinePlus: Complex Carbohydrates
- International Journal of Environmental Research and Public Health: Simple vs. Complex Carbohydrate Dietary Patterns and the Global Overweight and Obesity Pandemic
- ChooseMyPlate.gov: What Foods Are in the Grains Group?
- WebMD: High-Fiber Diets and Weight Loss
- Nutrition: A Nonrestrictive, Weight Loss Diet Focused on Fiber and Lean Protein Increase.
- USDA: Basic Report: 20080, Wheat Flour, Whole-Grain (Includes Foods for USDA's Food Distribution Program)
- USDA: Basic Report: 20081, Wheat Flour, White, All-Purpose, Enriched, Bleached
- Glycemic Index Foundation: What Affects the GI Value?