Reducing the amount of carbohydrates you eat is a surefire way to lose body fat. The great thing about lower carb diets is they reduce appetite so you automatically eat fewer calories. They also improve insulin sensitivity, which is key because high insulin levels inhibit fat loss.
But as great as lower carb diets can be for getting you lean fast, there can be some drawbacks:
* People enjoy eating carbs because they taste good. After all, carbs are just different chemical forms of sugar.
* Carbs can elevate mood because they are used in the production of the neurotransmitter serotonin, which makes you feel good.
* Lack of carbs during highly stressful times can lead to elevated cortisol. Adding in some low-glycemic carbs can help fight stress.
* Very low-carb diets can lead to reduced thyroid function when accompanied by fat loss, leading to a slower metabolism and other physiological problems.
Therefore, it’s reasonable to try to eat as many carbs as possible and still get the fat loss results you want. Plus, everyone is unique, and recent research shows that some people get better results with higher carb diets, whereas others have a very hard time losing fat unless they go low-carb.
Insulin Sensitivity Predicts Fat Loss
In fact, studies show that the amount of fat you will lose from a diet is most determined by your insulin health. If you are more insulin resistant, it’s very unlikely you will be able to lose fat with a high-carb, calorie-reduced diet. You will get better results with a lower carb diet.
But if you are more insulin sensitive, you have more flexibility to include carbs. You may be able to lose just as much fat with a higher carb intake, especially if you are exercising properly.
For example, a recent trial classified women as insulin resistant or insulin sensitive and put them on either a low-fat, calorie-restricted diet or a low-carb diet. The low-carb diet didn’t require calorie restriction due to the fact that the women in the low-carb group naturally ate much fewer calories than normal. Among the insulin resistant women, only those on the low-carb diet lost any fat. They reduced body fat percentage by an average 2.3 percent.
The women who were classified as insulin sensitive lost roughly the same amount of body fat regardless of whether they were on the low-carb or low-fat diet (the low-carb group lost an average 3.2 percent body fat and the low-fat group lost 2.7 percent, which is not a statistically significant difference).
We can make a few conclusions from this study and related research:
* If you are insulin resistant, following the traditional “diet” that is calorie restricted but high in carbohydrates will actually undermine your ability to lose body fat.
* If you are very insulin resistant, cutting carbs a little bit, or playing around with small reductions in your glycemic load probably won’t have any effect. You need a more radical approach to reset your metabolism.
* People who are sensitive to insulin have a lot more flexibility in the type of diet they use to lose body fat. This suggests that the key is to optimize insulin sensitivity first.
How Carbs Affect Insulin
You probably already know that after a meal, your blood glucose rises depending on how many carbs, protein, and fat you ate. Insulin is a hormone that is secreted by the pancreas in order to help store glucose either as muscle glycogen (the energy source for the muscle) or as fat. The body “prefers” to replenish glycogen first, only storing excess glucose as fat if glycogen stores are full.
Carbohydrates come into it because they tend to elevate blood glucose the most (more than protein or fat), triggering a large release of insulin. Of course, there are many different carbs.
Refined and liquid carbs spike blood glucose much more than fruits or vegetables. Large elevations in blood glucose are a problem because the body tends to overestimate the amount of insulin necessary and releases too much.
If you have frequent large elevations in insulin, your cells become resistant to it. More insulin is needed for the same amount of glucose and the body is more likely to store the glucose as fat.
This is the reason the women in the study who were insulin resistant couldn’t lose fat even when they reduced the amount of calories they ate by 340 a day for the duration of the study. They had very high fasting insulin and it didn’t improve over the course of the study. Because more than 50 percent of those calories were from carbs, their bodies just deposited the carbs as fat.
What’s interesting is that the insulin resistant women who ate the low-carb also began the diet with high fasting insulin. But, eating a low-carb diet for a year resulted in a 65 percent reduction in fasting insulin by the end of the study. Not only did the women lose body fat, the low-carb eating “repaired” their metabolisms.
How Exercise Affects Insulin
The next step for these women and anyone who wants to be able to maximize the amount of carbs they can eat and still lose fat is to work out. Exercise has a profound effect on insulin sensitivity.
Working muscles are powered by stored carbs (known as glycogen). After you work out, your muscles are ready to replenish those stores, which means the muscle tissue is very sensitive to insulin and ready to use any carbs you eat for glycogen rather than fat.
Another reason working out is critical is that it increases muscle mass. At rest, muscle consumes the majority of the glucose transported in the blood (70 to 90 percent). For every 10 percent increase in muscle mass, you get an 11 percent increase in insulin sensitivity.
This means that anaerobic forms of exercise such as strength training or sprints will improve insulin sensitivity the most because they improve muscle mass percentage. Endurance exercise works too. The catch is that you only experience major benefits in trained muscles, so if you’re a runner, you’ll be fairly insulin sensitive in the leg musculature, but less so in the upper body.
Therefore, it’s important to do some form of total body exercise. Strength training is pretty much a no-brainer as your best option because combined aerobic and resistance programs improve insulin sensitivity more than aerobic training alone.
How to Figure Out How Many Carbs You Need
This can be tricky since it’s hard to know how insulin sensitive you are. Therefore, it’s recommended you get either a fasting insulin test from your doctor, or test your fasting glucose with glucose test strips, which can be purchased at a pharmacy.
Ideally, fasted glucose should be between 70-90 mg/dl, with a goal of below 84 mg/dl. If you’re above 90 mg/dl, you need to work on managing your glucose, which should improve your insulin sensitivity.
Below are some basic carb guidelines that work for many people. Remember that everyone is unique and it’s important to experiment. Plus, there are many different kinds of carbs:
* Low carb vegetables, which don’t need to be restricted.
* Fruit, which runs the gamut from low- to high-carb. Because fruit contains a lot of water and fiber, most people can include 1 or 2 pieces of higher carb fruit in moderately low-carb diets, depending on what else is included in the diet.
* Foods like nuts, seeds, avocado and beans that have small amounts of carbs. They can be included on low-carb diets, but the carbs must be accounted for.
* Starchy vegetables and grains are high in carbs but also contain fiber and can be included in small quantities in moderately low-carb diets. These are potatoes, sweet potatoes, rice, quinoa oats, and other grains.
* Refined carbs that include bread, cookies, crackers, juice, soda, and just about anything packaged. These should be avoided on low-carb diets.
Category A: You’re sedentary and have a lot of weight to lose.
You are probably fairly insulin resistant. Start with less than 50 grams a day of carbs because this will lead to the production of ketones, allowing for significant improvements in insulin sensitivity.
You’ll need a high-protein and fat intake from healthy sources, which should reduce appetite and allow you to avoid getting hungry.
Carbs to eat:
* As many leafy green and other low-carb vegetables as you want.
* Select fruits such as berries or pomegranate.
* Tiny amount of carbs from nuts, seeds, avocado, beans used as condiments.
Other people who may benefit from going below 50 grams of carbs a day:
If you are sedentary, have a crappy, high-carb diet, and want to lose fat, a very-low carb diets can help you get more insulin sensitive.
However, if you have poor eating habits already, it can be very challenging to have to transform them while also slashing carbs. Depending on how you adjust to changes, it may work better to focus on removing the unhealthiest carb sources from your diet and eating high-quality meals consistently.
Category B: You work out but are overweight.
You also probably need to get more insulin sensitive. Try the 50 to 100 grams of carbs a day range. This range can also be useful for sustaining body composition without much struggle once you’ve improved your insulin health.
Carbs to eat:
* As many leafy green and other low-carb vegetables as you want.
* Low-carb fruit and small amounts of carbs from nuts, seeds, and beans.
* A couple of servings of higher carb fruits or starch-based carbs. For example, a medium potato has about 35 grams of carbs, a sweet potato has about 25 grams, and a half-cup of rice has 22 grams.
Also consider: It’s great you are already working out, and you may benefit from getting more serious with training. A total body higher volume program that is geared to building muscle and creating metabolic stress will dramatically help you improve insulin sensitivity so you can eat more carbs.
Category C: You are active and fairly lean.
If you’re active and fairly lean but want a way of eating that makes sustaining body composition easier, try 100 to 150 grams a day. You need to be fairly insulin sensitive for this to work, making it most appropriate for people who lift weights intensely or do a decent amount of physical activity throughout the day.
Carbs to eat:
* All the vegetables you want.
* All the low-carb fruit you want.
* Beans, nuts, seeds, and avocado in reasonable amounts.
* A few pieces of higher carb fruit and starchy foods.
Category D: You’ve been eating very low-carb for a long time.
If you’ve been restricting carbs for awhile and have either plateaued, or don’t feel great, you may benefit from making a change. Many things are possible:
* Calories could be too low (but don’t assume this unless you are accurately tracking calories).
* You could be experiencing some unbalanced hormones (a moderate elevation in insulin triggers satiety and leads to the release of leptin, an appetite reducing hormone).
* You could have unhealthy gut bacteria due to lack of indigestible fiber that comes from vegetables, fruit, and resistant starch.
* Thyroid hormone, cortisol, or neurotransmitters could be off..
Depending on your physical activity level and body fat percentage, you could try increasing your carb intake to the 100 to 150 gram range or stay on your low-carb diet but cycle in higher carb days in which you eat significantly more carbs (say up to 200 grams, though some people may want to go even higher of they work out).
Category E: You’re a hard charging athlete who wants to strip the fat off.
You have a lot of options and you need to determine how much pain you want to deal with. Additional considerations are whether you’re in the off-season or need to be at your best to compete.
A low-carb ketogenic diet could get you lean fast (elite male gymnasts tried it in one study and got down to about 5.5 percent body fat in a month). This would require you to push through some challenging workouts due to low glycogen stores.
Carb cycling also yields fast results: Try anywhere between 150 and 300 grams of carbs on hard training days and go below 100 on off /recovery days. This can help maintain training performance quality and avoid the mental struggle of low-fuel stores.
Final Points: When you cut carbs, you obviously need to increase protein and fat. If you’re going for a ketogenic diet that increases the use of fatty acids for energy, you need your fat intake to be high because this will “shift” the body to burn more fat.
For protein, get at least 1.6 g/kg of body weight because this amount has been found to preserve lean muscle mass during rapid fat loss in lean, active people.
To do low-carb right, you need to be eating unprocessed foods: vegetables, meat, fish, eggs, some dairy, and select fruits, nuts, beans, and seeds.