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CANCER, WATER and WEIGHT: the importance of hydration through cancer and weight management

Dehydration is a common side effect of cancer treatment and it occurs when your body loses more fluid and electrolytes than it takes in. Our bodies are nearly 60% water, so water is our lifeline.

#Dehydration also can result from exposure to excessive heat, sweating, not consuming enough fluids, medication side effects or the cancer itself.

Why is staying hydrated important for cancer patients?

Water is our nutrient transportation system…Fluids carry nutrients to cells, flush bacteria from the bladder and prevent constipation. Water is also necessary for normal body function and for muscle, connective tissue and joints to move correctly.

Staying hydrated makes treatment side effects less severe and lowers your chances of missing or delaying cancer treatments. If you get dehydrated and it is not addressed, you could it could lead to severe complications, such as seizures, swelling of the brain, kidney failure, shock, coma and even death. Since dehydration can stop normal body functions and be quite dangerous, staying hydrated during treatment is important for protecting your organs from long-term damage.

What are the signs of dehydration?

Some of the signs that you might be dehydrated are:

  • feeling thirsty

  • experiencing dry mouth, lips, gums, and nostrils

  • increased headaches

  • dizziness

  • confusion

  • sleepiness

  • decreased energy

  • muscle cramps

  • darker urine color

  • decreased urination

  • decreased skin elasticity

  • low blood pressure

  • increased body temperature

How do you know if you’re drinking enough water?

Each of us has different fluid needs as our bodies change. For cancer patients, fluid needs depend on many factors, such as the type of cancer treatment you’re undergoing, and whether you are dealing with a fever, diarrhea, vomiting or other gastrointestinal side effects, but a general recommendation is to drink half of your bodyweight in ounces. (I.e. if you weigh 150lbs, a recommended water goal is 75oz)

Another way to make sure you’re hydrated is the urine test — if your pee is clear, you’re doing well… the darker yellow / brown it is, the more dehydrated you are! There are exceptions to this because certain medications and vitamins may cause color changes in your urine. For example, some multivitamins cause it to be bright yellow, some chemo meds like AC (aka red devil) cause it to be red, etc.

Dehydration and weight gain:

Did you know that being dehydrated can actually cause you to gain weight? Water weight that is.

It seems counterintuitive, but dehydration actually causes your body to hold (retain) more water. When you’re dehydrated, your body responds by holding on to as much fluid as possible. Water retention is your body’s natural response to store water so it can function properly. That means water weight actually increases when you’re dehydrated. In fact, dehydration is one of the main causes of water weight gain.

Hydration and weight loss:

Not only can dehydration cause you to gain water weight, drinking water can actually help you to lose weight. Here are some reasons why:

Water is a natural appetite suppressant. When the stomach is full, it sends signals to the brain to stop eating. Water can take up that space in the stomach, leading to a feeling of fullness and reducing hunger. Oftentimes, our bodies confuse hunger with thirst, and we think we’re hungry when we are actually thirsty and needing water.

Water increases metabolism (aka increases calorie burning). This means that drinking water can increase the number of calories you burn, even at rest. Studies have shown a 2-3% increase in the number of calories burned in the 90 minutes of drinking water.

Water helps to remove waste from the body. Water helps the kidneys function properly and flush toxins and waste, while retaining essential nutrients and electrolytes. Water helps to soften / loosen harden stool and flush waste from your body and being dehydrated can lead to waste building up leaving you feeling bloated, swollen and tired which adds extra inches and extra weight.

Water is necessary to burn fat. Without water, your body can’t properly metabolize stored fats. The process of lipolysis (breaking down fat) requires water. The first step in this process is called hydrolysis, which essentially adds water to the fat to break it down, so without water, your body cannot break down fat.

Tips to help increase your water intake:

  1. Carry a water bottle with you wherever you go. Seeing your bottle and carrying it with you will be a constant reminder to drink your water! I recommend getting a reusable bottle that is appealing to you and has a spout/mouthpiece that is easy for you to drink out of. Whether you’re at home, at work, running errands, at the gym or wherever you are, keep your water bottle with you.

  2. Start your day off with a cup of water. Before you eat, drink or do anything else, begin your day with water! For even more benefits, make that first cup of water lemon water. Lemon water helps with digestion, boosts immunity, regulates your body's pH levels, detoxes your liver, is a natural anti-inflammatory and curbs your appetite.

  3. Track your water intake. People tend to overestimate how much water they’re taking in, so tracking how much water you’re actually drinking will help you stay on track. You can use an app on your phone (like myfitnesspal, fitbit, etc.), write it down or do whatever works for you! As I mentioned earlier, the goal varies for each individual, but a general goal is to drink half your bodyweight in ounces of water.

  4. Add some flavor. Sometimes you just want some flavor and variety and sometimes water just isn’t appealing (like when you’re going through chemotherapy — I know for me, there were times when water actually tasted awful to me!). There are many ways to flavor your water these days, but unfortunately, many of these options contain artificial sweeteners and food dyes, so be careful about your source of flavor! Infusing your water with fruit (like oranges, lemons, lime or strawberries), with cucumber slices or mint leaves will give you good variety.

Grab your water bottle, fill it up, get drinking and make it a great day. :)


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