fiber & fat loss: it works! but don't go to extremes

If you’ve never thought about fiber as something that can help with fat loss, think again.


Fiber is wrongfully underrated, and for most people, it's a fat-loss wonder! Sounds fake, but adding more fiber to their diets has helped my clients curb cravings, push past weight loss plateaus, and have better energy throughout the day. But the reason so many people (my clients included) notice such a difference when they increase their fiber intake is because they weren't getting nearly enough to begin with!


I'm backed by the statistic that 95% of Americans are not eating the recommended 25-30g fiber per day, so I'm going to assume it's something you’re probably not getting enough of either. Certain diets have recently come under controversy for giving the impression of "the more fiber, the better!". The results are appealing, but before you go searching for the highest fiber options of everything you eat, you should remember too much of anything is not good.



What is fiber?


Fiber is a type of carb (along with starch and sugar), and is found in several foods both naturally and as an added ingredient. Increasing fiber intake is something I talk about frequently with my clients - for reasons that range from lowering cholesterol to getting better sleep - but since fiber affects everyone differently, I don’t often give recommendations outside of one on one conversations...


HOWEVER, I’ve recently been getting sooo many DMs from you asking for advice for bloating, constipation (yep - prep yourself for a lot of 💩 talk), having zero energy, hitting a weight loss plateau, constantly craving cool ranch doritos… the list goes on. 


Getting enough (but not excess) fiber seems to be a universal fix for many of the questions I get, so I figure it’s time I dive a little deeper and give you the scoop. 


You wouldn’t think so, but fiber is complicated AF. 


Eating more high fiber foods is a lot more intricate than it sounds, and there are a few prerequisites you should know before you get started.


  1. There's no need to overload on fiber! Actually, I’m begging you to please not do this unless you’re ready to welcome stomach cramps, bloating, and gas (note that this can also happen if you try to use supplements and fortified foods instead of the real thing). No matter where you’re starting from, you’ll want to increase your intake slowly, and focus on doing so from whole food sources first. I recommend my clients gradually increase fiber until they reach an intake of 35g per day. That's enough.

  2. Before you make any moves to increase your fiber intake, make sure you’re staying hydrated! Fiber is a fat loss unicorn because it keeps our GI system moving, but if you’re not hydrated, that doesn’t happen. Without beating around the bush - if you don’t drink enough water you’re going to get constipated AF and no one wants that. 


Let’s circle back to what you said about “fat loss unicorn”. Tell me more…


Eating more fiber is one of the best ways to increase your metabolism. Why? Because you don’t get calories from fiber. So What? High fiber/low cal foods (ex. vegetables) fill your stomach and tell your metabolism to start digesting. Digestion, in and of itself, burns calories, which is why you’ll hear me say things like “eating more fiber revs your metabolism!”. What else? Well, since your metabolism is revved up, but the high fiber foods don’t contain calories, you will start to burn calories from other sources (i.e. body fat). Another bonus? Your stomach filling up on high fiber foods sends a signal to your brain that you’re full, so you’ll naturally eat less calories. AND if you’re like me, and eat with your eyes first, having a lot of volume will help trick your brain into feeling full, and boost the satiety factor of your meal.


Okay, sign me up! How do I get more fiber in my diet?


There are several different ways to categorize the type of fiber found in foods, and most foods fit into more than one of these categories! I think it will be most helpful for me to break down two ways that fiber may be categorized:

  1. Soluble vs Insoluble

  2. Dietary vs Functional


Soluble vs Insoluble Fiber


There are two primary distinctions when it comes to types of fiber: soluble, and insoluble. The ratio of insoluble:soluble fiber found naturally in foods varies, and the foods I list under each category below have a majority of the specified type of fiber, but likely contain both!

  • Insoluble fiber: If you struggle to go to the bathroom regularly, this will be the kind that will help! Insoluble fiber is indigestible (not cute to talk about, but it goes looking the same way as when it comes out), triggers motility of food through our digestive system, and will help prevent and treat constipation. These are the foods that add volume and promote fullness in the way I mentioned above!

  • Wheat Bran/Oat Bran

  • Whole Grains

  • Potatoes

  • Cabbage, Cauliflower, Broccoli, Brussels Sprouts

  • Soluble fiber (again, not cute but must be said) pulls in water and softens stool. As it’s digested, it forms a gel that will slow the rate at which carbs enter our bloodstream. This is great news for you because this will stop your blood sugar from spiking, and decrease feelings of hanger and insatiable cravings. Another bonus of soluble fiber is its ability to slow absorption of dietary fat and cholesterol, which not only helps with weight management, but also reduces cholesterol levels and risk of heart disease. Here is a list of foods that naturally contain more soluble than insoluble fiber.

  • Rolled Oats 

  • Lentils, Peas, Beans

  • Chia Seeds, Nuts

  • Carrots, Berries

  • Tofu

Why is this not what I see on a food label?


(Side Note!) I want you to start trying to understand food labels more closely. This is one thing I have all of my clients do and I’m AMAZED at the questions they come up with. It’s a confusing topic, but if you take a picture and send me your questions I’d be happy to answer! 




Dietary vs Functional Fiber


When you look at a food label, you see “total fiber”, which is the sum of both dietary (natural) and, if applicable, functional (added) fiber in the product. 


Dietary fiber is the kind naturally found in vegetables, fruits, whole grains, legumes, nuts, and seeds. Functional fiber is added to products to boost fiber content (think bars, powders, breads, crackers, and other supplements). This doesn’t mean functional fiber is bad! In fact, some functional fibers may actually be extracted from natural sources... 

  • Naturally Occurring Functional Fiber: psyllium, beta-glucan, inulin (chicory root), tapioca, pectin

  • Artificially Created Functional Fiber: polydextrose, wheat dextrin, methylcellulose, guar gum

These sound like nitty gritty details, but it’s important that you’re aware of the difference - especially if you’re someone who always seems to have negative GI side effects after eating a FiberOne bar, but are totally fine if you eat an alternative fiber bar that uses a different source of functional fiber. (note: this is also why, if you struggle with GI issues, keeping a food journal that includes symptoms can be super helpful!)


To tie this into what you previously learned: both dietary and functional fiber may contain insoluble fiber, soluble fiber, or both. If you look on your ingredients list you may see...

  • Insoluble Functional Fiber: cellulose, methylcellulose, root vegetables

  • Soluble Functional Fiber: tapioca, guar gum, chicory root fiber, inulin, resistant starch, wheat dextrin, psyllium, beta-glucans

Again, the difference between soluble vs insoluble may make a difference in how you tolerate the fiber. You may associate feeling bloated with functional (added) fiber, when it could be the difference between soluble vs. insoluble. 


What type should you be getting more of? 


That depends on what your needs are and what, if anything, you’re sensitive to! Not all fiber is created equal, and different types work for different people. If fiber is what is lacking from your diet, you likely need more of both. Getting your overall fiber consumption to the minimum recommended intake is most important, but it’s a lot to unpack. I work with my clients to gradually increase fiber intake to help with fat loss, while also making sure other nutrients aren't sacrificed! You should work with a professional before you make drastic changes to your diet, especially if you’re more interested in seeing sustainable results!