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Gastrointestinal Transit: How Long Does It Take?

Gastrointestinal Transit: How Long Does It Take?

How long does food stay in my stomach? How long is it before a meal reaches the large intestine? The answer to such commonly-asked questions is not necessarily simple.

First, there is considerable normal variability among healthy people and animals in transit times through different sections of the gastrointestinal tract. Second, the time required for material to move through the digestive tube is significantly affected by the composition of the meal. Finally, transit time is influenced by such factors as psychological stress and even gender and reproductive status.

Several techniques have been used to measure transit times in humans and animals. Not surprisingly, differing estimates have been reported depending on the technique used and the population of subjects being evaluated. Some of the techniques used include:

  • Radiography following a barium-labelled meal. Sequential radiographs can be used to determine when the front of the barium label reaches different regions of the digestive tube. Such meals are not very physiologic and the technique exposes the patient to repeated exposure to radiation.
  • Breath hydrogen analysis. A number of carbohydrates are very poorly digested or absorbed in the small intestine, but readily fermented by bacteria when they reach the large intestine. Fermentation liberates hydrogen gas, which diffuses into blood and is exhaled in breath, where it can be readily measured. Thus, after consumption of a meal containing a non-absorbable carbohydrate (lactulose or, more commonly, baked beans), there is a large increase in exhaled hydrogen when the carbohydrate reaches the large intestine. This provides an estimate of pre-colonic (stomach plus small intestine) transit time.
  • Scintigraphic analyses. Meals containing pellets or colloids labelled with a small amount of radionuclide (99mTechnetium, 113mIndium, etc.) are consumed, and the position of the radioactive label is sequentially monitored using a gamma camera.

Studies of gastrointestinal transit have clearly demonstrated two related phenomena important to understanding this process:

  1. Substances do not move uniformly through the digestive system.
  2. Materials do not leave segments of the digestive tube in the same order as they arrive.

In other words, a meal is typically a mixture of chemically and physically diverse materials and some substances in this mixture show accelerated transit while others are retarded in their flow downstream.

An example of how ingested substances spread out in the digestive tube rather than travel synchronously is shown in the figure below. These data were obtained from a human volunteer that ingested a meal containing 111Indium-labeled pellets, then measuring the location of the radioactive signal over time by scintigraphy. It is clear that parts of the meal are entering the colon at the same time that other parts are still in the stomach.

The discussion above should help to explain why it is difficult to state with any precision how long ingesta remains in the stomach, small intestine and large intestine. Nonetheless, there have been many studies on GI transit, and the table below presents rough estimates for transit times in healthy humans following ingestion of a standard meal (i.e. solid, mixed foods).

50% of stomach contents emptied

2.5 to 3 hours

Total emptying of the stomach

4 to 5 hours

50% emptying of the small intestine

2.5 to 3 hours

Transit through the colon

30 to 40 hours

Remember that these are estimates of average transit times, and there is a great deal of variability among individuals and within the same person at different times and after different meals.



  • Camilleri M, Colemont LJ, Phillips SF, etc. Human gastric emptying and colonic filling of solids characterized by a new method. Am J Physiol Gastrointest Liver Physiol. 257:284, 1989.
  • Charles F, Camilleri M, Phillips SF, etc. Scintigraphy of the whole gut: clinical evaluation of transit disorders. Mayo Clin Proc 70:113, 1995.
  • Degen LP and Phillips SF. Variability of gastrointestinal transit in healthy women and men. Gut 39:299, 1996.
  • Iwanaga Y, Wen J, Thollander MS, etc. Scintigraphic measurement of regional gastrointestinal transit in the dog. Am J Physiol Gastrointest Liver Physiol 275:904, 1998.
  • Metcalf AM, Phillips SF, Zinsmeister AR, etc. Simplified assessment of segmental colonic transit. Gastroenterology 92:40, 1987.
  • Proano M, Camilleri M, Phillips SF, etc. Transit of solids through the human colon: regional quantification in the unprepared bowel. Am J Physiol Gastrointest Liver Physiol 258:856, 1990.
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Beach Season and Covid-19

Beach Season and COVID-19

(Contributed by Linda Anegawa, MD, FACP )

Summer is in full swing, and for many of us, a beach trip is a family tradition. But how should we proceed in these uncertain times?

1. Is it safe to go to the beach at all?

Currently, the word “safe” must be used as a relative term. We are dealing with a novel Coronavirus and limited testing – so other than staying home 100% of the time and having no contact with outsiders, there isn’t any way to determine if any activity is truly “safe.” Having said that, by taking precautions, any activity can be made “safer” when it comes to the risk of contracting viral infection. You are also probably safer from the virus when outdoors in the sunlight (where it is thought that the virus may die quickly) vs. in a closed environment such as a restaurant or theatre.

2. What are the risks?

The risks of going to the beach include the presence of large crowds which impact your ability to social distance, people shouting or yelling which can theoretically spread more virus particles in the air than vs. normal talking, having to use public restrooms with lots of high-touch surfaces which can harbor the virus, or lying in sand where someone may have sneezed or coughed.

3. How can I prepare, should I decide to go?

• Read up on your local area’s cautions and restrictions before you go. Some counties have strict rules on the number of people who are allowed on the beach, what you can bring, and there could be time restrictions, too.

• Keep your beach visit activity-focused… go for a walk, swim, or a paddle. When you are moving and far from others, your risk of catching the virus is lower. Plus, you’ll get in some exercise which is critical for mood, stress, and sleep, and can help lower inflammation.

• Social distancing remains the mainstay of preparation. Your likelihood of viral infection is dependent on the amount of virus in the air or on surfaces + duration of contact, so this is key. Try to find the least crowded area that you can. Avoid areas where it looks like there are large parties or other gatherings.

• It’s ideal to continue wearing a mask at all times unless in the water.

• Avoid public chairs or benches. Bring your own beach chairs and equipment. Bring plenty of hand sanitizer or wipes in case you need to use a public rest room.

• Avoid setting food and beverages directly in the sand. Bring a folding table with you or a large blanket. And of course, to maximize your metabolic health, be sure to bring healthy low-carb snacks to fuel your body such as small packets of nuts and dried seeds, hard boiled eggs and cut veggies.

• When you get home, wash everything in hot water with detergent and dry in the dryer.

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BMI (Body Mass Index)

BMI (Body Mass Index)

(Contributed by Linda Anegawa, MD, FACP )

The BMI, or Body Mass Index, is one of the most commonly used measures to identify people whose health is at risk from excess weight.

But despite its near-universal use by medical practices and hospitals, BMI can be one of the most misleading measurements when it comes to health risks. How is this possible?

First, let’s define what the BMI is. BMI is simply equal to your weight in kilograms divided by your height in meters squared. Typically, a BMI of 19-25 is considered normal. Those with a BMI of 26-29 are considered to be overweight, and those with a BMI 30 or above are considered to be suffering from obesity.

At first glance these categories may seem helpful to us. You might assume that the higher the BMI, the less healthy the person is, and sometimes that is in fact the case. However, as it turns out there are serious flaws with relying only on BMI.

As an illustration: let’s take the case of two individual men:
(1) A 22 year old, 6 feet 4 inch tall professional linebacker with the NFL who weighs 300 pounds.
(2) A 65 year old, 5 feet 1 inch tall secretary who weighs 190 pounds.

You might guess that these two men sound like they’d have very different bodies which is clearly the case. However, despite their vastly different physiques, these two men in fact have the exact same BMI – 36! They’d appear to be identical using a health scale that relies on BMI as a measure.

In addition, both the football player’s and the secretary’s BMIs of 36 would place them in the range of morbid obesity per standard guidelines. But as I mentioned, the BMI doesn’t tell us whether most of their weight is made up of fat, muscle, bone, or water weight, otherwise known as body composition. For example, the typical pro athlete has a body fat percentage under 10% making them extremely lean, regardless of BMI. As we get older, more of our body composition shifts towards fat, and we lose lean mass. BMI alone is unable to account for this.

Also, as it turns out, even if these two people had the same body fat percentage, where the fat is located on the body makes a very big difference in predicting health risk. For example, fat located around the middle of the body, known as ‘visceral fat,’ puts one at higher risk of cardiovascular-related death, even with a normal BMI [1]. So just because one has a BMI under 25 does not necessarily mean one is safe from metabolic disease.

One final thing that BMI doesn’t account for is whether each person’s weight causes health problems. One could have a higher BMI and yet be free of health conditions. On the other hand, some individuals with lower BMIs have very significant weight-related diseases such as prediabetes and type II diabetes, hypertension, or abnormal cholesterol. We don’t know exactly why that is, but it’s likely that genetics, ethnicity, activity levels, and even environmental factors all play a role.

Using BMI therefore can make it extremely difficult to tell who is at risk from their weight, and who is healthy. Doctors especially Obesity Medicine specialists, have recognized this, and are turning to other measures to help. Here are some examples of other methods which are growing in use:

(1) Waist -to-Hip Ratio: this simple, inexpensive measure is easy to do at home or in your doctor’s office. To obtain it, you simply measure your waist at the level of your navel, and your hip at the widest portion, then divide. A ratio of 0.9 or less is best for men, and 0.85 or less is healthiest for women.

(2) Body Composition Analysis, or BCA: BCA readings are able to determine how much of a person’s makeup is fat, versus muscle, bone, and water. Healthy body fat percentages for men are anywhere from 10-20% and for women, 22-33%. Segmental BCA machines are also able to estimate the degree of visceral (belly) fat one has, which as we know raises health risks.

(3) Edmonton Obesity Staging System: not a measurement, but the Edmonton system allows doctors to estimate risk based on whether weight-associated medical problems are present and the severity. For example, a smaller person with a higher Edmonton Stage is at much higher risk of problems than a larger person with a lower Edmonton Stage. [2]

The BMI simply doesn’t tell the whole story. Fortunately, Obesity Specialists have taken the lead in advancing newer ways to assess weight-related health risks in order to provide critical attention to those who need it the most.

(1) Ann Intern Med. 2015 Dec 1;163(11):827-35. doi: 10.7326/M14-2525. Epub 2015 Nov 10.
(2) CMAJ. 2011 Oct 4; 183(14): e1059–e1066.
doi: 10.1503/cmaj.110387

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Keep Your Blood Sugar in Balance

Keep Your Blood Sugar in Balance

Sugar is the fuel that powers cells throughout the body. Blood levels of this energy source ebb and flow naturally, depending on what you eat, how much you eat, and when you eat. But, when something goes wrong and cells aren’t absorbing sugar effectively, the resulting high blood sugar can damage nerves, blood vessels, and organs.

The A1c blood test measures average blood sugar level over the previous three months. A normal reading is below 5.7%. A reading between 5.7% and 6.5% indicates prediabetes and a reading above 6.5% indicates diabetes. Any reading above normal means that toxic amounts of sugar are building up in your bloodstream.

Often, high blood sugar causes no obvious symptoms, at least at first. However, as more sugar circulates in the blood, the body tries to get rid of it by spilling the excess sugar into the urine which draws water out of the body. So, one of the first signs of high blood sugar is frequent urination and increased urine volume.  This, in turn, causes dehydration making you thirsty. Some people also feel extremely hungry and may have headaches.  Another early symptom of high blood sugar is fatigue.  A person with high blood sugar can feel tired, weak and sleepy while performing normal day-to-day activities.

The longer-term complications of chronic high blood sugar (diabetes), are well-known and affect the body from head to toe.  High blood sugar, untreated, causes serious irreversible damage to your eyes, kidneys, brain, and cardiovascular and nervous systems.  Diabetes is the major cause of limb amputations.

Many people don’t know they have diabetes because the symptoms build subtly over time.  But, being attentive to the early signs of high blood sugar can prompt you to have an A1c test.  If the A1c test confirms high blood sugar seek treatment immediately to avoid serious health consequences down the road. 

The best approach, of course, is prevention.  Adopt lifestyle habits that naturally keep your blood sugar in the healthy range.  Maintaining a healthy weight, eating right and exercising regularly all contribute to keeping your blood sugar in check.

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Be in Control of Emotional Eating – Insight and Tips

Be in Control of Emotional Eating – Insight and Tips

(contributed by Linda Anegawa, MD, FACP)

We all eat emotionally to some degree, and it’s not necessarily pathological.
Soothing ourselves with treats has roots in childhood. Anyone remember a parent handing you a lollipop after you fell off your bike and scraped your knee? Or making you soup when you were sick? These associations can become firmly rooted for life. After all, certain foods are known as “comfort foods” for a reason.

For some of us, our tendency to reach for snacks whenever we hit a rough patch becomes a concern. This can occur after a string of difficulties, or a personal trauma. In addition, even chronic low-level exposure to stress in our normal daily lives can lead to more snacking than normal. Over time, we may find ourselves reaching almost unconsciously for food in response to any unpleasantness at all. Food distracts us from feeling the pain, the sadness, the loneliness, the irritability, the boredom. One patient told me, “food filled the empty place inside me” following the death of her mother. The emotional eating can then become more and more entrenched over time.

Whatever the reason for over-indulging, the end result is often similar.   

Any soothing effect of food is only temporary, and the negative emotions/stressors are still there for us to face.  Plus we begin to feel guilty or ashamed about setting back our health goals, and then we beat ourselves up.    This is how emotional eating sets us up in a vicious cycle.

Here are some ways to begin to break free:

(1) Start a journal.  You may wish to try tracking what you eat – tracking can increase awareness of both your physical hunger and non-hunger eating triggers.   There are some great apps for this, or even a simple notebook will do.   Tracking can give us a “hunger reality check”.  For example, if you had a full meal 1 hour ago, it’s highly likely that the hunger you have is more emotional than physical.

(2) Practice Mindfulness.  Giving yourself the opportunity to pause for even 5 seconds prior to eating is important.  Try to take one slow deep inhale and exhale before taking a bite.  Notice physical and mental sensations.  Keep breathing slowly as you eat, chewing each bite of food at least 10 times.  Notice how your body feels as your stomach becomes more full with each swallow of food. 

(3) Make it easier on yourself.  Get rid of the foods that lead you astray – don’t buy trigger foods such as sweet or salty snacks, especially from big-box stores that sell them in giant bags.  Nothing is a bargain if it makes you feel angry at yourself for eating it!

(4) Set regular mealtimes.  Due to our hectic lifestyles and tendency to multi task, we rarely sit down to just eat and do nothing else.  This can worsen mindless and emotional eating.  Even committing 15 minutes for a lunch break for example is far better than wolfing down something from the drive-thru while on errands.

(5) Focus on FATS, proteins, and greens – these help us to feel more physically full so the temptation to graze and snack won’t be as strong.  A large tossed salad with a protein of choice and olive oil dressing makes a great lunch, and it’s quick and easy to prepare. 

(6) Watch for boredom.  When that restlessness starts to settle in, keep a list on your phone of things to do to distract yourself so you won’t eat.  Take a quick 10 minute walk, or call a friend, paint your nails, take a shower, etc. – ANYTHING to avoid snacking when you really don’t want to.

(7) Know when to get help.  Consider therapy to help learn better coping skills or to help handle severe stress. A trained psychotherapist can also screen you for an eating disorder such as Binge Eating or Night Eating Disorder. Even if you don’t have one of these though, the road to lifestyle change can be filled with speedbumps and setbacks, so highly qualified support can be critical for your long term success. 

For support and resources right now, the National Eating Disorders Association provides trained helpline volunteers that you can call or text. For community support, join our private Facebook group where others who have struggled with emotional eating challenges provide support and encouragement based on their personal health journeys. CLICK HERE for a comprehensive guide to the signs of an eating disorder, common treatments, etc.

You aren’t alone in this struggle, reach out today!

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Social Eating Tips


(contributed by Linda Anegawa, MD, FACP)

Have you ever struggled to say “NO” at family gatherings and other social events, when you’re offered food that you know is not good for you?

It’s a fact that even when loved ones know you’re trying to lose weight and get healthier, we often feel pressured to make a bad choice, have seconds, or eat dessert.  This doesn’t necessarily mean that others want to sabotage you or ruin your success – it can just be history, culture, and a habit of food being a gift to share with those you love.

Here are some things you can say at social gatherings to stay on track with your wellness goals, when you’re offered something you don’t want to eat:

“I sure wish I could have some!  But I’m so full, from all the other delicious food right now.  Maybe a little later.”

“Thanks, I’ll pass and just keep you company while you enjoy!”

“No, thank you” (firmly, without explanation at all).

When offered seconds: “No, thank you, it was delicious.  Can I have the recipe?”

“No thanks.  Hey, how are your kids doing – I haven’t seen them lately!” (diversion tactic!)

“You know, I realized that my stomach doesn’t feel good when I eat _____, so now I try to avoid feeling like that.”

“I have _____ (high cholesterol, prediabetes, etc.) so I’m making changes in what I eat to improve my health.”

“My doctor told me I can’t eat that, but it smells amazing!”

If you feel a need to explain, or are pushed further, you can say “Sorry, that just doesn’t agree with me” or “Sorry, I need to choose what I eat more carefully for my health.”

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How to Survive Cold and Flu Season on a Low-Carb Diet

How to Survive Cold and Flu Season on a Low-Carb Diet

(contributed by Linda Anegawa, MD, FACP)

Have you noticed everyone around you is starting to sniffle and sneeze?  Here are some tips to prevent getting sick, and what to do if you do end up with a bug.

1. Prevention is key! Keep your water intake up. If you aren’t getting the minimum 64oz. of water per day start with that as your goal. Then add more water until you are drinking 1⁄2 your body weight in ounces of water every day! Drinking lots of fluids, water, unsweetened tea, clear broths, & rehydration solutions like Powerade Zero may help.

2. Wash your hands frequently and wipe down your keyboards, door handles and phones.  Carry hand sanitizer wherever you go and use it frequently.

3. Medications & Remedies: If you do get sick, look out for carbs and sugars in over-the-counter medications and treatments.   Always read the labels on medications and look for the ones that are sugar-free or low in sugar. Did you know 1 pack of Emergen C has 5 carb grams including 4 grams of sugar. A cough drop has 3 or 4g of carbs – so popping 10+ a day will add 30g of carbs or more. Nyquil liquid has 19g of carbs per serving!  When in doubt, ask your pharmacist whether a medication is sugar-free and alcohol-free.

4. Brands to try: Hyland’s DEFENSE Cough & Cold (sugar free, dye free, alcohol free) OR Theraflu Sugar Free Nighttime Severe Cold & Cough, OR Nyquil capsules- not liquid form.  There’s also Hall’s Sugar Free Honey and Lemon (no aspartame!).  Remember, while these may be sugar free, you should still limit them as much as possible. Compare labels of all brands and look for carbs and sugars hidden in the medications! Tylenol, aspirin, and ibuprofen can also be helpful if needed.  One of the simple solutions to relieving throat symptoms rather than purchasing these medications is by gargling salt-water solution. Simply mix 1⁄2 teaspoon of salt in a cup of water. What’s more, you’ll save money.

5. Foods to eat: Try plain chicken broth, soft boiled eggs and unsweetened hot tea.  Stevia-sweetened electrolyte drinks like Vitamin Water Zero can help keep up your hydration and soothe sore throats.

6. Rest! You’ve heard it before but getting enough rest and sleep every day will help in your recovery. When the body is sleeping, it’s healing!

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Can I drink Alcohol on a Low Carb Diet?

Can I Drink Alcohol on a Low Carb Diet?

(contributed by Linda Anegawa, MD, FACP)

The short answer:  yes, but…

First, discuss with your doctor whether the use of alcohol may negatively impact your health.  Potential dangers include interacting with medications you may be taking and/or worsening certain chronic conditions you may have such as fatty liver, gout, and hypertension.

Should you and your doctor feel that occasional alcohol is safe for you, it can be enjoyed in moderation as part of a low carb lifestyle.  For example, there are lower-carb alcohol options that you can choose such as dry wines and spirits.  You can also use sugar-free mixers to enjoy low-carb variations of your favorite drinks like a rum and diet coke or a Moscow Mule made with diet ginger beer.

Remember however, that even if your doctor feels moderate alcohol is safe for you, it still can stall or greatly slow weight loss.   

General rules for alcohol use with low-carb diets:

  1. Choose dry wines (cabernet, pinot noir, chardonnay, Chablis, zinfandel), champagnes, spirits and (very) low carb beer if any beer at all. Remember to only combine with sugar-free mixers.

  2. Limit your consumption. Too many drinks can not only add up in calories from the alcohol but also limit your ability to steer clear of the dessert tray or reaching for snacks when you’re not hungry. Know the size of your pour and be aware of your limit!  We generally advise patients to stay under 1 drink per day.

  3. Try to avoid dessert wines like ports and sherries due to high sugar content. Likewise, avoid fruit-flavored cocktail mixers and dark beers. 


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Magnesium: A Mineral that Matters

Magnesium: A Mineral that Matters

(contributed by Linda Anegawa, MD, FACP)

You may know magnesium as a mineral that is important for the function of all our muscles:  low magnesium levels may cause painful cramps in our arms and legs, particularly after we’ve done very intense exercise.  Magnesium is also critical for the function of our heart muscle, and when our levels get too low, serious arrhythmias may result. 

Magnesium is also critical for over 300 other metabolic and enzymatic reactions in the body.   In particular, the relationship of magnesium to blood sugar levels is an area of active study.  As a part of glucose metabolism, magnesium drives many of the reactions in the process of breaking down blood sugar.  

Magnesium deficiency is known to aggravate insulin resistance, because without magnesium, more insulin is required to metabolize blood sugar.  The pancreas pumps out more insulin, driving fat storage and increased hunger, leading to increased food intake.   When an individual is insulin resistant to begin with, the presence of low magnesium levels can feed an ongoing vicious cycle of worsening insulin resistance.

Some smaller studies have shown that giving individuals who are insulin resistant magnesium supplements improves insulin sensitivity and improves blood sugar control.  Whether magnesium can outright prevent diabetes or cause weight loss on its own is not completely clear.  While they don’t quite recommend supplements to prevent diabetes, the American Diabetes Association recommends that people with diabetes consume increased quantities of magnesium-rich foods.  These include vegetables and legumes, for example.

If you eat a lower carb or ketogenic diet, you may experience increased urination which means that you will lose extra water-soluble minerals including Magnesium.  So, remember the importance of this vital mineral.  You’ll be doing your muscles and your heart a favor, and maybe even put a damper on the cycle of metabolic syndrome that previously blocked your weight loss efforts. 

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Low Carb Travel Tips

Low Carb Travel Tips

(contributed by Linda Anegawa, MD, FACP)

Travel can be exhausting, even more so when you are committed to a healthier lifestyle. Even with careful planning, the unexpected can throw a wrench into things.  Canceled flights, traffic delays, and schedule changes are just a few of the things that can play havoc with your dietary plans.

Here are the best ways to set yourself up for success:

  1. Be Prepared

No matter how big or small the trip, having on-the-go food options will relieve a lot of stress.  Have a meal before leaving home, bring backup snacks, and seek out low-carb options.  Sticking to the basics can help you stay on plan and keep you from getting overwhelmed. Most restaurants and grocery stores will have healthy protein choices and vegetables available.

Look for a bun-less burger with salads, or a grilled protein with veggies and olive oil – it doesn’t have to be fancy.  Remember, proper trip preparation takes practice, but it will get easier over time.

  1. Do your food recon beforehand

Before leaving for your trip, scope out the food scene where you’re going.  Websites like TripAdvisor or Yelp are great resources for this!  And most restaurants have their menus available online.  You can even call a restaurant ahead of time to inform them of your dietary needs.  Most chefs will appreciate the opportunity to be better prepared to serve you, and don’t be afraid to ask for modifications.    

  1. Assert your needs – don’t be afraid to ask for what you want

Traveling with family or colleagues can be especially challenging.  It can be helpful to explain beforehand why you’re committed to a low-carb lifestyle.  The more people understand why you’re making the choices you are, the more likely they’ll be to support you and they may even give it a try themselves.  Another tip: try grocery shopping together for what you want when you arrive.

  1. Move past slips

Even when we try our best, sometimes we go a bit off plan. If you do, it’s important not to spend time beating yourself up. Show yourself some compassion – acknowledge you did the best you could under the circumstances, and then determine to make the next good choice to help you get back on track.

  1. Most of all – enjoy yourself!

At the end of it all, trips and vacations are meant to be enjoyed. Brainstorm ahead of time all the ways to have a good time there that don’t involve food. Go on a hike or walk to explore your new area. If you’re visiting loved ones, focus on spending time with them.  Try not to be obsessed about every meal…just do your best. 

Happy Travels!