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Can You Drink Lemon Water While Fasting?

"Michael Philips is a California-based professional with a Ph.D. in Molecular Biology, who is also a trained sports nutritionist and certified personal trainer. He is an accomplished professional in the academic and commercial sectors, with a focus on scientific communications and education over the past decade. He is experienced in the research, development, and marketing of ingestible consumer goods and medical devices, and is passionate about the intersection of science and human health."

Just like making lemonade, iced tea, coffee, or any other of your favorite beverages, lemon water can be made differently depending on your own personal taste. If you’re someone who prefers more of a sweet taste, the additional sugar (or honey) may actually break your fast. However, if you prefer a flavor that is tarter, your lemon water may be low enough in sugar to continue your body’s fasting state. 

The United States Department for Agriculture FoodData Central database [1] states that an 8 fluid ounce glass of water containing the juice of a typical 48g (gram) lemon contains the following:

Calories

10.6 kcal

Carbohydrates

3.31 g

Sugars

1.12 g

Protein

0.168 g

Fat

115 mg

Vitamin C

18.6 mg (21%DV)

In addition, the U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is 3.7 liters (125 ounces) per day for men and 2.7 liters (91 ounces) per day for women [2]. A potentially easier, and more individualized, recommendation to consider is to drink 0.5 ounces per pound of body weight, as it’s estimated that you get nearly 20% of the liquids you need from your food [3]. This would mean that a person weighing 150 pounds should drink at least 75 ounces per day on average. The great news is that your liquid intake will not only count toward this total amount of recommended fluid intake, but you can also decide to make your serving into a 12 or 16 fluid ounce serving (or larger!) by just increasing the amount of water in your cup, while still using the same amount of lemon juice.

Types and Benefits of Lemon Water

The benefits of lemon water lie primarily with the benefits of water itself. It is a major component of our everyday fluid intake and is necessary for our body’s normal function. In addition, an increased amount of liquids included into your daily routine is often at the expense of sweetened caloric beverages, which are associated with lower energy intake, meaning you can save calories by swapping out your sweetened beverage (even lightly sweetened beverages) for water [4].

Acidity, Temperature, Fructose: Does It Matter?

To understand how drinking lemon water affects your metabolism, we need to look at some of the components of lemon juice. 

Acidity:

The first question that needs to be answered is does lemon juice break a fast?

According to a recently published paper by researchers from Université Paris-Saclay in France, lemon juice not only significantly lowered the mean blood glucose concentration peak by 30% but delayed it by more than 35 min compared to water alone [5]. This agrees with other recent research that showed that pH levels of a meal can affect the digestion of starch through the activity of an enzyme found in saliva. It also highlights that fasting can still play a part in the improved insulin sensitivity found with traditional intermittent fasting [6]. What this could mean in relation to drinking lemon water, is that even though it contains some calories, without the addition of any extra sugar, it may be a good option as a beverage, while also providing some flavor to shake up your day.

Temperature:

Chilled water or other beverages contract blood vessels and can lead to slowed digestion. If you think back into your high school physics class, you may also remember the laws of thermodynamics. While sparing you the details and taking you back into a place in your mind that you’ve taken years to forget, your body will spend more energy during the transfer of thermal energy. And what we know is that the energy that your body “uses” in everyday activities such as digestion counts toward your metabolism, and ultimately how many calories you burn in a day.  The same concept is in play when thinking about the added energy your body needs to use when digesting more dense objects (such as a dense wheat cracker) versus that of a less dense object (such as an air-puffed wheat snack).

Fructose:

Finally, let’s address fructose, the sugar that is commonly found in fruits. Not all sugars cause the same response in the body. Fructose has a low glycemic index, which means that it doesn’t cause a rapid rise and fall in blood glucose levels, and therefore doesn’t significantly increase insulin levels. With the juice of a single 48-gram lemon containing 0.528g of fructose [1], the metabolic response of drinking lemon water in a healthy adult will be quite minimal, allowing your body to continue in a fasting state. And even when potentially breaking a fast with lemon water with added honey, there are still some benefits to overall body composition and uric acid levels [7],[8].

Will Lemon Water Break a Fast? Dependence on Fasting Variations

Intermittent fasting (IF) is a dietary plan that alternates between periods of eating and fasting on a daily schedule. Any type of diet can fit into an IF regimen (i.e. low-fat, low-carbohydrate, ketogenic, vegetarian, etc) because the overall goal of intermittent fasting doesn’t have anything to do with what you eat. Rather, IF is determined by when you eat and the length of the gap between your meals. Those gaps between meals are your “fasts”. Fasts can be placed into your day when they are most convenient, therefore being “intermittent”, meaning that they can be irregular and not completely structured to be the same each and every day. In short, it’s a type of dietary plan that can be adapted to each individual’s lifestyle and provides some flexibility for when surprises come up in your work or personal life.

Lemon water can be looked at in the same way. Based on how you choose to make it, it can continue your fast, or break it, while also providing hydration and a bit of energy in the form of sugar and calories to keep you going. And remember, if added lemon helps you get to your recommended daily liquid consumption better than pure water alone, it’s ok to give your tastebuds a little treat. Strategies like this may help you get through your fasting periods more easily and help you manage your calorie intake once you get to your mealtime.

So, does lemon water break a fast? Or stated in a different way, “Can I drink lemon water during intermittent fasting”? The short answer is YES, you can drink it during a fast. If you drink it with no added sugar or honey, it does not break your fasting state. In fact, it can be a great option to help you push through your longer windows and keep you hydrated between meals!

References:

1. https://fdc.nal.usda.gov/fdc-app.html#/food-details/167747/nutrients

2. https://www.nap.edu/read/10925/chapter/1

3. https://www.eatright.org/food/nutrition/healthy-eating/how-much-water-do-you-need

4. Stookey, Jodi D., et al. "Replacing sweetened caloric beverages with drinking water is associated with lower energy intake." Obesity 15.12 (2007): 3013-3022.

5. Freitas, Daniela, et al. "Lemon juice, but not tea, reduces the glycemic response to bread in healthy volunteers: a randomized crossover trial." European journal of nutrition 60.1 (2021).

6. Sutton, Elizabeth F., et al. "Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes." Cell metabolism 27.6 (2018): 1212-1221.

7. Shetty, Prashanth, A. Mooventhan, and Hongasandra Ramarao Nagendra. "Does short-term lemon honey juice fasting have effect on lipid profile and body composition in healthy individuals?." Journal of Ayurveda and integrative medicine 7.1 (2016): 11-13.

8. Wang, Hongjing, et al. "Lemon fruits lower the blood uric acid levels in humans and mice." Scientia Horticulturae 220 (2017): 4-10.

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