Why Do Low Carb and Keto Diets Work?

So why do low carb diets work for weight loss? I often hear it explained like this: if you cut the carbs out of your diet then your body has to look elsewhere for its primary energy source. So it goes to look for your stored body fat to use as energy and that means that you lose weight. But it goes a bit deeper than that so let’s dig in!

This week, I want to talk about why low carbohydrate diets work, and work well. There is a lot of evidence showing how well  they work compared to the old low fat or low calorie diets. Low carb diets are leading the pack with statistically significant weight loss in randomized controlled trial studies. These studies are the gold standard of Research. So why is that?

Low Carb and Keto Diets are a Solution to the Broken Model

First, the conventional approach is flawed - the calories in, calories out approach. Basically, it says you’re consuming too many calories and not burning enough calories. You gain weight, so the easy solution to that is to simply eat less and move more to create a calorie deficit, and bam! - your problems are solved…! Except it doesn’t really work like that. Long term, most people have trouble sticking to a strict weight loss program. Many people who do stick to a weight loss program lose a minimal amount of weight and most put it back on within a year or two.

When we restrict calories/nutrients, our bodies get hungrier and when we don’t eat, our metabolic rate decreases. If you don’t give in and eat then your metabolic rate goes down and weight loss stops. So now you think you need to reduce calories even further. You start to feel tired and even more hungry. Eventually you give in and eat because you can only sustain a low calorie diet for so long.

Low carb addresses this dilemma with blood sugar control which allows your hormones to balance out. That allows your body to tap into stored body fat for energy, so you aren’t hungry and now you’ll start to lose weight!

Reducing Your Insulin Levels

The number one reason low carb diets work so well, is that they reduce blood sugar and therefore insulin levels. Insulin, the fat storage hormone, is produced in the pancreas is triggered when we eat carbohydrates. The Pancreas secretes insulin to help shuttle blood glucose around the body to be used as energy.  Insulin impacts several hormones but it’s what also signals the body to take glucose from our bloodstream and put it into our fat cells as stored body fat for later use when it currently isn’t needed. If we reduce our carb intake, the pancreas produces less insulin.

During the first few days of a low carb diet, you’ll lose mostly water weight as your body starts depleting your glycogen stores. When blood glucose and insulin go down, your kidneys no longer need to hold onto fluids. This is why blood pressure goes down while following a low carb or keto diet. Our bodies store carbohydrates for the short term in the form of glycogen. Glycogen is stored in the liver and in the muscles. Along with glycogen, water is stored, When your body dumps the water, the water flushes out electrolytes. This takes a few days to a week which is why initially there is a big weight loss for some.

Using Low Carb to Reverse Insulin Resistance

Insulin resistance is where the body is ignoring the effects of insulin, so your pancreas must secrete more insulin to do the same job of keeping blood sugars in check. Eventually your body can’t keep up and you develop prediabetes which eventually  leads to type 2 diabetes. Many who struggle with obesity are insulin resistant and this keeps them in fat storage mode. A low carb or ketogenic diet are both very effective for reversing insulin resistance.

Reduced Appetite

This is one of the biggest benefits of a low carb lifestyle. There are a couple of hormones involved in appetite regulation – leptin, the satiety hormone and ghrelin (think growling!) the hunger hormone. When you feel full on a low carb diet, it feels very different then full on a high carb diet.  With low carb, the protein and fat intake will have you feeling satiated much sooner and longer than a high carb diet. When you eat a high carb diet, you feel full because your stomach is full but you often don’t feel satiated. When you eat a low carb diet, you’re typically eating very nutrient dense food instead of empty calories. A low carb diet carries you much longer without the blood sugar roller coaster and the afternoon energy dip that has you grabbing for a cup of coffee or sugary snack to give you a boost.

As your appetite is reduced, you will tend to start intermittent fasting naturally since you just aren’t hungry. You may also find you only need to eat two meals a day. Many people simply don’t feel hungry first thing in the morning. When you start paying attention to your hunger, you’ll find that you probably don’t get hungry till lunch time. When you fall into this pattern of eating just lunch and dinner, you’re now intermittent fasting – you’re consuming your food in a 6 – 8 hour window and not eating the rest of the time. Intermittent fasting is great because when your fasting, your insulin levels are going to drop, and your body can access stored fat for energy.

Metabolic Advantages

Low carb diets are effective because they give us a metabolic advantage. A recent randomized control study divided people in two different diets – one group was high carb and the other group was low carb. Indeed the low carb diet group burned 200 calories a day more than the high carb group!

Food and Sugar Addiction

Low carb and ketogenic diets are very effective at helping curb food addiction. When I first went low carb and consequently  keto, I could not imagine living without bread, potatoes, or pasta. But these foods kept my blood sugar on a roller coaster, and it was hard to consume those foods and not have blood sugar spikes. When I stopped eating those high carb foods, almost all my cravings went away. Now if I don’t eat the high carb foods, I don’t crave them. The same goes for sugary treats, if you stop eating them your cravings will go away. Keep feeding that sugar monster, you’ll continue to crave it. Now I’m not saying that low carb or keto cures food/sugar addiction, but it has made a HUGE difference for me. You have nothing to lose by trying right?

So, the health benefits and takeaways as I see them are that low carb takes the blood glucose spikes (and corresponding crashes) out of the equation, balances your hormones,  kickstarts weight loss (because you aren’t in fat storage mode) AND makes you feel great! What’s not to like?