Ketosis and Aspartame

The keto diet is a great fat loss diet.
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The keto diet is extremely low in carbs, but you can still enjoy a can of diet coke and other sugar-free foods or beverages. Aspartame can replace sugar in most products, but is it keto-friendly? This additive does contain some carbs and may kick you out of ketosis when used in excess.


What Is the Keto Diet?

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From athletes and gym-goers to nutritionists, millions of people swear by the keto diet for fat loss. This dietary plan was initially designed for children with epilepsy, Dravet syndrome, infantile spasms and other conditions. Today, it's a popular choice for those who wish to get leaner and keep the pounds off.

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Read more:7 Things Nutritionists Want You to Know About the Keto Diet

According to a February 2014 review featured in the ​International Journal of Environmental Research and Public Health​ (IJERPH), ketogenic diets have been proven effective in the battle against the bulge. Additionally, they may help improve blood lipids and certain cardiovascular risk factors. Several types of ketogenic diets exist:

  • Standard ketogenic diets limit carbs to about 10 percent of total daily calories.
  • High-protein ketogenic diets limit carbs to 5 percent of daily energy intake.
  • Targeted ketogenic diets encourage the consumption of carbs pre- and post-workout.
  • Cyclical ketogenic diets alternate between high-carb days and low-carb diets.


The standard keto diet and high-protein ketogenic diets are the most widely used, according to a September 2018 review published in the ​Indian Journal of Medical Research​ (IJMR). Other versions, such as targeted ketogenic diets, appeal to athletes. These weight loss plans use carb cycling to provide the energy needed for regular exercise and to replenish glycogen stores.

Generally, ketogenic diets are high in fat, low in carbs and moderate in protein. Some versions go below 20 grams of carbs per day, which limits your food choices. You may still eat small amounts of veggies and low-carb fruits, such as berries; however, whole grains, legumes, potatoes and sugary desserts are off-limits. Dieters can fill up on meat, fish, eggs, butter, coconut oil, heavy cream and even mayo or bacon.


Ketosis and its Symptoms

What makes the keto diet so effective is its ability to induce ​ketosis​. This metabolic state kicks in after a few days of fasting or extreme carbohydrate restriction, points out the ​IJERPH​ review.

When you cut down on carbs, your liver begins to produce ketone bodies, such as acetone and beta-hydroxybutyric acid. Your brain and body can use these compounds for fuel in the absence of glucose.



Note that ketosis isn't the same as diabetic ketoacidosis. The latter is a life-threatening complication of diabetes and occurs when ketones reach dangerously high levels, warns the Mayo Clinic.

According to the ​IJERPH​ review, ketone levels in the body are very low (about 0.3 millimoles per liter) under normal conditions. The central nervous system can use these compounds for energy when their levels reach about 4 millimoles per liter. Dieters may use a blood ketone meter, a ketone breath meter or urine strips to measure ketone levels.


Another way to tell whether or not you're in ketosis is the so-called keto flu. Most dieters experience headaches, fatigue, brain fog and other flu-like symptoms as they enter this metabolic state.

Nausea, dizziness, muscle soreness, changes in bowel habits, diminished mental focus and cramping are common, too. These symptoms vary from one individual to another and may last a week or so — or up to one month in extreme cases, states Intermountain Healthcare.


Luckily, there are ways to manage the keto flu and relieve its symptoms. Simple things, such as drinking plenty of water, filling up on fats and taking electrolyte supplements, can make all the difference. Also, make sure you get adequate rest and engage in light exercise.

Is Aspartame Keto-Friendly?

Ketosis occurs in response to an elevated production of ketone bodies. Common mistakes like eating too much protein or hidden carbs may kick you out of ketosis and hamper your weight loss efforts. The whole point is to deprive your body of glucose, its primary source of energy.


As the Academy of Nutrition and Dietetics points out, your body breaks down ketones for energy when no other source of fuel is available. Normally, your energy comes from carbs, which are converted to glucose after ingestion.


When you're on a low-carb diet or fasting, protein can be used for fuel, keeping you from reaching ketosis. Therefore, it's important to watch your intake of protein and carbs while filling up on dietary fats.

Sugar is off-limits, but you may use natural or artificial sweeteners to satisfy your cravings. Aspartame, for example, is about 200 times sweeter than sugar and can be found in hundreds of foods and beverages, including:

  • Chewing gum
  • Diet coke
  • Flavored water
  • Sugar-free pudding
  • Sauces
  • Breakfast cereals
  • Certain medications, such as cough syrup

Contrary to popular belief, aspartame isn't calorie-free, reports the International Food Information Council Foundation. A typical 1-gram serving provides almost 4 calories and 1 gram of carbs. However, since it's much sweeter than sugar, consumers typically use less of it.

For example, Equal, a low-calorie sweetener containing aspartame, has less than 1 gram of carbs per serving (1 packet), so it's unlikely to kick you out of ketosis unless you go overboard. Furthermore, aspartame has no effect on energy intake and blood sugar levels, according to a meta-analysis published in ​Critical Reviews in Food Science and Nutrition​ in August 2017.

These findings show that aspartame is a safe choice on the keto diet — when used in moderation. But this doesn't mean it's good for your health. Like most additives, it has some drawbacks.

Safety Concerns Regarding Aspartame

According to the International Food Information Council Foundation, aspartame is likely safe for healthy individuals, including children and pregnant or breastfeeding women. Since it doesn't raise blood sugar, it can be consumed by individuals with diabetes. Furthermore, there is no link between aspartame and cancer.


However, if you have phenylketonuria, you may need to avoid this additive. Phenylketonuria is a genetic disorder that affects the body's ability to break down phenylalanine, an amino acid in aspartame and other foods. This additive may also cause headaches in susceptible individuals, but more research is needed to confirm it.

The current evidence is conflicting, though. For example, a research paper published in the September 2017 issue of ​Nutrition Reviews​ suggests that aspartame may not be as safe as it was once thought. This sugar substitute may increase oxidative stress and disrupt the body's antioxidant balance, leading to inflammation. In the long run, it may affect brain function, including learning and memory, even when consumed in moderate amounts.

Note that most studies reporting these findings were conducted on mice, so take them with a grain of salt. The Food and Drug Administration and other health organizations state that aspartame is safe and unlikely to cause adverse effects, points out the International Food Information Council Foundation.

Keto-Friendly Alternatives to Aspartame

Aspartame isn't your only option. Stevia and sucralose are keto-friendly too. If you prefer a natural sweetener, consider using stevia. This non-caloric sugar substitute, which comes from the plant with the same name, is considered safe and may facilitate weight loss, reports a May 2015 review featured in ​Nutrition Today​.

According to the Mayo Clinic, most sugar substitutes, including stevia, don't affect blood glucose levels. Therefore, they are suitable for keto dieters. The only exceptions are xylitol, maltitol, erythritol and other artificial sweeteners containing sugar alcohols, which may increase blood glucose.

What about Orbit, Extra and other sugar-free chewing gum brands containing sorbitol? Is sorbitol keto-friendly? Not really.


This additive is a sugar alcohol and may raise blood glucose levels when consumed in excess, especially in people with type 1 diabetes. Bloating, gas and diarrhea are common side effects, warns the FDA.

Another problem with sorbitol is that it's about 60 percent as sweet as sugar, according to the Calorie Control Council. Therefore, you may end up using too much of it, which can increase your daily carb intake. Aspartame, by comparison, is 200 times sweeter than sugar, so you need only a small amount to satisfy your sweet tooth. Sorbitol, however, can withstand high temperatures during cooking, making it ideal for baked goods.

Read more:Artificial Sweeteners Linked to Weight Gain, Not Weight Loss

Stevia and artificial sweeteners, but not sugar alcohols, are the best choices for keto dieters. Generally, the calories in sugar alcohols come from carbohydrates. Artificial sweeteners, on the other hand, contain few or no carbs and calories. You may consume small amounts of sorbitol and other sugar alcohols while on the keto diet, but there are better alternatives available.

Beware of Hidden Sugars

Just because you're on the keto diet doesn't mean you have to skip desserts. From low-carb keto cupcakes and flourless chocolate cake to peanut butter cookies, there are plenty of delicious recipes you can try

To make things easier, bake your own desserts at home rather than buying them from the store. Many so-called diet foods contain hidden sugars that may kick you out of ketosis.

A November 2012 study published in the ​Journal of the Academy of Nutrition and Dietetics​ assessed the use of caloric and noncaloric sweeteners in packaged foods. After analyzing more than 85,000 products, researchers concluded that 74 percent of them contained added sugar in one form or another.

About 68 percent of packaged foods were made with caloric sweeteners, 6 percent contained both caloric and non-caloric sweeteners and just 1 percent contained only non-caloric sweeteners. Most products were formulated with cane sugar, fruit juice concentrate, corn syrup and other sugar substitutes that can skyrocket insulin and blood sugar levels.

Read more:Curious About Keto? Start With These 10 Recipes

High-fructose corn syrup, for example, contains almost equal parts of fructose and glucose, two forms of sugar. It's the most widely used caloric sweetener in processed foods and provides about 11 grams of carbs and 7 grams of sugars per serving (0.56 ounces). This additive may contribute to diabetes, weight gain, obesity and insulin resistance when consumed in large amounts.

Every gram of sugar matters when you're on the keto diet. The only way to avoid hidden sugars is to carefully read food labels and check the ingredients list. Deli meats, canned vegetables and soups, fast food salads and other processed foods may contain sugar too, so opt for whole foods instead.