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Surgery Preparation Diet

Your surgeon has prescribed and will monitor you while you complete a two-week, 800 calorie a day liquid diet using Numetra meal replacement shakes or puddings. Any questions or concerns while on the program should be directed to your surgeon.

Step One:

Go to a Positive Choice clinic location to get your meal replacements:

Monday-Thursday (closed Friday)
7:30 – 4:30 pm (closed 12 -1 pm)

Monday and Tuesday only
7:30 -4:30 pm (closed 12:30 – 1:30 pm)

Wednesdays only
9- 4:30 pm (closed 12:30 – 1:30 pm)

Thursdays only
9- 4:30 pm (closed 12:30 – 1:30 pm)

Step Two:

Select and pay for your meal replacements.

You will select a combination of 10 meal replacement boxes (7 packets per box) from the following flavors:

  • Chocolate
  • Vanilla
  • Strawberry
  • Mocha

Your 2 week meal replacement program will cost $220. You will pay when you order your meal replacements.

Step Three:

Begin your meal replacement program 2 weeks before your surgery. We have provided detailed instructions for preparing your meal replacements below. Read all information because you also have specific fluid requirements to meet each day to protect your health and to feel your best.

Review the common questions below.

Contact your surgeon with any further questions or concerns. Positive Choice will not be monitoring you on this program.

About this program

Every day you will have 5 meal replacements evenly spaced throughout the day along with plenty of fluids. You will have no other food while on this program. This program will significantly reduce your calories and overall carbohydrate intake, preparing your body for surgery. Eating additional foods will compromise your results and lead to cancellation of your surgery. 

How to prepare your shakes:

You will mix powdered meal replacement shakes with water, coffee, or carbonated drinks (like sparking water or diet soda). You can mix with any amount of water you prefer, generally 8-20 ounces. Shakes can be made up to a day in advance if kept cold. You can add sodium free and calorie free spices (like cinnamon, pumpkin pie spice, peppermint extract, sugar free syrups).

You can mix with cold water, blend with ice, or make a hot drink. Or you can prepare a pudding.

To make warm drinks: Slowly add warm water or coffee to the powder and create a paste. Slowly add more water while stirring carefully. 

To prepare a pudding: Mix shake powder with 6 ounces of water and store in the fridge until cold. You can also put it in the freezer for a bit.

Tip: Purchase a milk frother to use to blend your shakes and make them creamy. Blender bottles are also great options for mixing shakes. Rinse and wash after use since protein drinks can quickly start to smell!

Drink 120-150 ounces of fluids every day. No more or less than this.

This includes what you use to prepare your meal replacements and anything else you drink during the day. You may have up to two cups of coffee or caffeinated drinks daily and you can mix your shakes into your coffee.

Tip: Purchase a gallon water jug (128 ounces) from the grocery store and pour all of your fluids from this. Or use measured bottles or cups to drink from to assure you stay within fluid requirements.

Have a meal replacement every 3-4 hours.

A regular and consistent schedule will maximize results and minimize hunger, cravings, and low energy. Avoid drinking too much before bed to reduce trips to the bathroom at night.

Tip: Set timers on your phone so you stay on schedule. Try setting everything you need for the day out on the counter or in your bag.

Common Questions (click to expand the section)

Constipation and Urination


You will pass less stools and your stools will probably be smaller and darker than normal while on meal replacements. Black, shiny, tar like stools should be reported to the medical staff.

It is very important to supplement your meal replacements daily with fiber to avoid constipation. You can use Calm™ Magnesium powder daily as well.

If you do experience constipation, meaning you do not have a bowel movement every 3 days, use a laxative (Ex-Lax ™, Milk of Magnesia ™, Correctol ™). Do not wait to use these options if you are constipated.


Because we ask you to drink 120-150 ounces of fluid a day and the meal replacements have a high protein content relative to carbohydrate content, you will have to urinate more often. If you struggle with nighttime waking to go to the bathroom, we suggest:

  • Finish your meal replacements 2.5 hours before bedtime or make your evening meal replacement with less water (pudding is a good option).
  • Drink most of your fluid before 4 p.m.
  • Do not consume less than 120 ounces of fluids per day, it puts your health at risk and will affect your results on this program. 
Nausea or Vomiting

Contact your surgeon, the Urgent Care clinic, or the Emergency Room. You may try the medications listed under Indigestion, but this is a symptom that should be further evaluated. 

Dizziness or Fatigue

Starting meal replacements and a very low calorie diet often causes the release of stored water from your body. You will maintain a mild state of dehydration on the program. This can cause occasional dizziness, a lightheaded feeling, or fatigue because of salt and fluid loss. 

To minimize the dehydration, get 120-150 ounces of fluid daily, avoid whirlpools, saunas, steam baths, hot yoga, and prolonged baths or showers while on meal replacements.

The occasional lightheadedness makes certain activities dangerous. Swimming alone, piloting a plane (flying in a plane is fine), motorcycle or bicycle riding, regular or scuba diving, and hang-gliding should be restricted.

Severe symptoms (if you fall or faint) require medical evaluation. Kaiser Permanente members should seek immediate medical attention from their medical provider, the Urgent Care clinic, or the Emergency Room by calling 1(800) 290-5000, 24-hours a day, seven days a week.


Try liquid antacids including Maalox™, Mylanta™, other brand names, or generic versions: two tablespoons up to four times a day.

You may also add over-the-counter products such as Tagamet™, Axiid™, or Pepcid AC™, taken according to the instructions on the package. 

Bad Breath

Losing weight means you are using your fat stores as energy. This will continue after surgery as well. When stored fat is metabolized for energy it travels in your blood in the form of ketones. Sometimes you can breathe out ketones through your lungs. You have experienced this when you have had “morning breath.”

While losing weight you can minimize “morning breath” by frequent and adequate water intake. 

Other suggestions to minimize morning breath include:

  • Frequent brushing of teeth, tongue, and gums.
  • Consuming a glass of water after each meal replacement. 
  • Use mouthwash, breath spray, or a product called Breath Assure™. Breath Assure no longer is sold. Now it is a product called “Mind Asure.”
  • Have 1-4 pieces of sugar-free gum or 1 to 4 sugar-free breath mints daily, being careful not to use the gum or mints as a food substitute. Note: too many artificially sweetened products in a day can cause stomach upset, gas, and diarrhea. 

Most people will feel some hunger and fatigue the first several days on meal replacements. Some will feel mild fatigue and hunger for a week or two. As you start burning predominately fat as your energy source you have a higher concentration of ketones in your blood stream which acts like a natural appetite suppressant.

Tips for minimizing hunger:

  • Consume all 5 of your meal replacements every day. If you miss one, have two at your next meal. Do not skip any!
  • Space them out evenly. Have your first meal replacement within 1-2 hours upon waking and then every 3-4 hours. Do not go longer than 4 hours without one unless you are sleeping.
  • Skipping meal replacements will slow weight loss and risk causing your body to metabolize muscle mass for fuel (which can damage your heart muscle and jeopardize your health).
  • Eating foods that are not a part of your program can make you feel hungrier and affect ketosis (a metabolic process where the body burns fat for fuel and that keeps you from feeling hungry). It can then take several days to return to this state after eating.
  • Do not eat any additional carbohydrates while on this program.
  • Too many artificial sweeteners, flavorings or caffeine can make you feel hungrier. 

Physical activity will help increase energy level, improve sleep, and maintain muscle mass while you lose weight. Mild to moderate aerobic exercise and muscle strengthening with light weights are recommended. Helpful tips include:

  • Go easy your first week and then gradually increase the intensity and/or duration of your exercise routine for the first several days on meal replacements as you may feel light-headed or tired. 
  • Warm-up and cool-down periods that include stretching help avoid muscle cramping.
  • A meal replacement taken 30 minutes prior to exercise helps avoid fatigue. 

Try the online exercise videos at or for an even greater selection of workouts visit the Positive Choice Integrative Wellness Center YOUTUBE channel. There are videos on cardio, yoga, simple yoga, strength training you can do at home, exercise for seniors, etc. Videos are 5 minutes, 10-15 minutes, or up to 45 minutes. There is something there for every fitness level.

Sugar Free Drinks and Sweeteners

You may use artificial sweeteners, but keep in mind that artificial sweeteners may cause sweet cravings, stimulate appetite, and possibly disrupt the balance of healthy bacteria in your gut making weight maintenance more difficult. If you choose to use artificial sweeteners, use as little as possible. If you experience nausea, bloating, or stomach upset, discontinue artificial sweeteners (diet sodas, gums, mints, etc.)