The Most Important Causes of Weight Regain after GLP-1 Weight Loss May Be the Easiest to Change

by Dr. Richard Lipman MD
Board Certified in Internal Medicine/Endocrinology

Weight regain after GLP-1 medications is common, with as much as 80% of dieters regaining the lost weight within 18 months of stopping the GLP-1 medication. In my experience, the most common rate of weight gain is approximately 2.5 lbs. per month after stopping any one of the GLP-1’s.
Many people think weight gain happens because they eat too much at meals or lack willpower, especially when tapering or stopping GLP-1’s.  In reality, that’s rarely the full story. Most people eat fairly well but often have a few foods or drinks that add more calories and carbs than they realize. Often the protein and fiber that were increased with the active weight loss are reduced. This results in the weight slowly creeping up by only about 2.5 lbs. a month. This is the result of eating an extra 7,000 calories a month, which amounts to only 210 extra calories per day. That can be as little as 2 tbsp. of olive oil, a glass of orange juice, half a bagel, or a bottle of regular soda

Foods and Drinks Causing Weight Regain After GLP-1’s

The foods and drinks responsible for this weight regain are outlined in Table 1 below.  This table does more than just list eight possible causes of weight gain. It ranks common habits based on two key questions:
  1. How much can this habit contribute to weight regain, especially after the initial weight loss with GLP-1s’?
  2. How easily can you replace it with a lower-calorie alternative?
This difference matters. The best place to start is usually with the habit that adds the most extra calories and is also the easiest to swap out for good. A small change you can stick with for years is usually better than a strict diet that only lasts a few weeks. The National Institute of Diabetes and Digestive and Kidney Diseases also recommends choosing an eating plan you can maintain long-term.
The weight-gain estimates in the table show what might happen if you add extra calories to your usual diet over time. These are not exact predictions. Real weight changes depend on your body size, metabolism, activity level, medications, age, and how your body adapts to changes in calorie intake. Still, the examples show how a small habit can add up over a year. Table 1 below shows the causes of the weight regain
Table I: causes of weight gain, in order of importance 

1. Soda and Juice: The First and Easiest Target

Soda and juice are listed first because they contain a lot of quickly absorbed sugar but don’t keep you full for long. A regular 12-ounce soda has about 150 calories and 42 grams of added sugar. Larger bottles, sweetened teas, fruit drinks, and specialty drinks can have even more. A 16 oz. of regular soda is 250 calories and 60 g of sugar.
Fruit juice might seem healthier than soda, but it can have just as much sugar and calories. Whole fruit has fiber and needs to be chewed, which helps you feel full. Juice takes away those benefits and lets you drink the sugar from several pieces of fruit in just a few minutes.
It’s easy to overlook liquid calories because many people don’t count drinks as part of their meal. A drink can add 150 to 300 calories without making you eat less food. The high sugar concentration alone can trigger instant hunger.
The good news is that this habit is one of the easiest to change. You can swap soda, sweet tea, and juice for water, unsweetened tea, black coffee, flavored sparkling water, or another zero-calorie drink. This way, you still get something cold or flavored without all the sugar.
This is a change to start with. It cuts a major source of calories without making you eat less or feel hungry for long periods. In fact, it produces a very important reduction in hunger and cravings.

2. Large Lunches With Refined Carbohydrates

A restaurant lunch with a burger, fries, and a sweet drink can easily add up to 800 to 1,000 calories. The bun, potatoes, breading, sauces, and drink all add a lot of carbs too.
This is where people often underestimate carbs. They might focus only on the hamburger meat and forget the bun, fries, ketchup, and drink. Altogether, these foods can add a lot of starch and sugar to one meal.
The table shows that even having one big lunch each week can add up over the year. You don’t have to skip lunch or just eat a small salad. Instead, try a more realistic swap like:e:
  • A burger without the bun and with vegetables instead of fries
  • Grilled chicken with a salad
  • A sandwich made with lower-carbohydrate bread
  • A protein and vegetable plate
  • Half of a restaurant portion, with the remainder taken home
  • Water or a zero-calorie drink instead of soda
The goal is to keep lunch enjoyable and convenient while cutting out the parts that add the most extra calories and refined carbs.

3. Skipping Breakfast—or Drinking Breakfast

Skipping breakfast isn’t always bad, and some people do fine with planned fasting. The issue comes up when you skip breakfast without a plan and end up having juice, sweetened coffee, or a high-calorie coffee drink instead.
Someone might say, “I don’t eat breakfast,” but still drink several hundred calories from sugar, cream, flavored syrup, or whipped topping. These calories are easy to miss and don’t keep you full for long.
For others, skipping breakfast can make them very hungry later in the day. This can lead to a big lunch, extra snacks, or overeating at dinner. The real question isn’t whether everyone needs breakfast, but whether your morning routine helps you control your appetite for the rest of the day.
If you need breakfast, a simple, protein-rich meal is usually better than juice, pastries, or sweet cereal. Eggs, Greek yogurt, cottage cheese, or a low-sugar protein shake can help control your appetite without adding lots of carbs.

4. The Wrong Breakfast

Bagels, muffins, and croissants are often seen as light breakfast foods, but many have as many calories and refined carbs as desserts. A large bakery muffin can have several hundred calories. A bagel can have as many carbs as several slices of bread, even before adding cream cheese, butter, or other toppings.
These breakfasts can be misleading because they don’t look like a full meal. They’re easy to eat quickly and often come with sweetened coffee or juice. As a result, breakfast can end up with hundreds of calories and lots of carbs, but not enough protein to keep you full until lunch.
You don’t have to skip breakfast. Instead, swap refined carbs for protein. For example, make a breakfast sandwich without bread, or replace a bagel with eggs, yogurt, or another easy protein option.
This is one of the most important changes for the GLP-1 diet..

5. Large Dinner Portions With Carbohydrates

Dinner portions have gotten bigger over time, especially at restaurants. The main issue isn’t usually the meat or fish, but the extra foods like bread, rice, pasta, potatoes, sauces, appetizers, and large side dishes.
Many people come to dinner very hungry because they didn’t eat enough protein earlier in the day. They end up eating a big meal quickly, before their body has time to feel full.
A better dinner doesn’t have to be small. You can have plenty of protein and vegetables, but cut back on large portions of starches. Try starting with the protein and veggies, then see if you still want all the rice, pasta, or potatoes.
Serving food directly onto your plate, rather than putting large bowls on the table, can help you avoid taking extra portions. At restaurants, try dividing your meal before you start eating.
The goal is a dinner that feels normal and satisfying, not a tiny meal that leaves you hungry or frustrated.

6. High-Calorie Snacks

Snacks can easily turn into an extra meal. Chips, nuts, cookies, candy, crackers, and snack bars are small, easy to eat, and often eaten straight from the bag or box.
Some snacks are labeled as natural, low-carb, or high-protein, but they can still have 200 to 400 calories per serving. Nuts are healthy, but a few handfuls can add up to more calories than you think. Protein bars can have as many calories and as much sugar as candy bars.
 The simplest fix is to avoid eating straight from a big package. Measure out one serving or buy single-serving packs. If you’re really hungry, pick a protein-rich snack, like Greek yogurt, cottage cheese, lean meat, or a good protein bar.

7. Hidden Calories From Oils, Dressings and Butter

Oils are one of the most commonly overlooked sources of calories. Olive oil is a healthier fat, but ‘healthy’ doesn’t mean it’s calorie-free. Fats are calorie-dense, and pouring oil into a pan or over a salad can add hundreds of calories without making your meal look bigger. They cause abdominal pain and nause when taking GLP-1 injections or pills.
The same goes for salad dressing, mayonnaise, butter, cream sauces, and dips. You might make a great salad, but you could double its calories by pouring dressing straight from the bottle.
These calories matter because they’re hard to spot. Most people notice a big serving of fries, but they might not realize how much oil goes into cooking—sometimes two or three tablespoons. Eliminate olive oil. They need to measure it. Use a teaspoon or tablespoon rather than pouring from the bottle. Choose a lighter dressing, serve it on the side, use a spray when appropriate, and reduce the butter added after cooking.
This is one of the easiest changes to make. You can enjoy the same meal with less added fat.

8. Alcohol: Calories That Are Easily Forgotten

Alcohol is another source of calories that people often forget. During active weight loss with GLP-1’s weekly, most people avoid alcohol simply because the GLP-1’s cause a markedly decreased desire for alcohol. I have seen this change in the post-weight-loss phase, when GLP-1s are stopped or reduced and excessive alcohol use returns.
Beer, wine, and spirits all have calories, even without sugary mixers. The National Institute on Alcohol Abuse and Alcoholism points out that alcoholic drinks add calories but few nutrients and can lead to rapid weight regain.
One drink may not seem like much, but the total over a week can add up. At home, servings are often bigger than a standard drink. In the U.S., a standard drink has about 14 grams of pure alcohol, which is the amount in 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof spirits. It may lower restraint and make high-calorie food more tempting. Drinks are often accompanied by chips, nuts, cheese, appetizers, or a restaurant meal. As a result, the calories from drinking may be much greater than those in the glass alone.
Practical steps include drinking less often, having fewer drinks, measuring your servings, or alternating each alcoholic drink with a glass of water. The best option depends on you, but alcohol should always be considered when looking at your calorie intake.

Begin With the Food Change Most Likely to Last

The main point isn’t to fix all eight habits right away. It’s better to find the one or two habits that add the most extra calories and pick realistic changes.
If you drink soda every day, switching to a different beverage can help more than trying a complicated diet. If you don’t drink soda, focus on restaurant lunches, alcohol, cooking oils, or evening snacks instead.
Ask three questions about each habit:
  1. How often does it occur?
  2. How many calories and carbohydrates might it add?
  3. Is there an acceptable replacement I could keep long-term?
The best first change is one that happens often, adds a lot of calories, and is easy to swap for something better.
Long-term weight control doesn’t come from being perfect. It comes from spotting the few habits that add the most extra calories and changing them in ways that still let you enjoy daily life. Swap out soda. Measure your oil. Cut back on alcohol. Change your breakfast. Eat less starch at restaurants.
When the new habit is simple enough to feel normal, you’re much more likely to stick with it and see lasting results.