How Much Weight Will I Lose on a Low-Carb Diet?

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People are attracted to a low-carb way of eating for a variety of reasons, but the most notable one is usually weight loss. How much weight can you realistically expect to lose?

The truth is that it's difficult to predict how much weight any one person will lose on a low-carb diet (or any other weight-loss diet, for that matter). There are simply too many variables at play. But here are some reasonable weight loss goals you can anticipate based on scientific evidence.

The Basics of a Low-Carb Weight Loss Experience

You may be surprised to hear that on a low-carb diet weight loss mainly happens in the same way as on any other weight loss diet by creating a calorie deficit (consuming fewer calories than you expend).

The difference is that while a low-calorie diet has an externally-imposed calorie limit, a low-carb diet works with your body so that you desire fewer calories. It's like changing the demand rather than the supply of food. 

Carbohydrate reduction seems to work on the appetite system in multiple ways, including altering levels of hormones and other transmitters of information about hunger and satiety in our body.

In terms of specific weight loss, some research suggests that people lose approximately the same amount of weight on a low-carb diet as on a low-calorie diet, even though they are not told to limit the amount of food they eat (just the amount of carbohydrate).

Getting Started

Getting started on a low-carb diet can be nerve-wracking. Hopefully, this information on what to expect in terms of weight changes your first month can ease your mind a bit:

The First Week of a Low-Carb Diet

The first week of a low-carbohydrate diet leads to a shift in the body's metabolism.

This is because the body has been using primarily glucose for energy and must switch to using primarily fat.

The good news is that some weight will be lost, but it's water loss, not fat loss. This is because the glucose which is stored for easy use in our liver is in a molecule called glycogen which is bound up with a lot of water. When initiating a low-carb diet, the number of glycogen stores are mobilized and broken down, and with it, goes some water weight. 

The weight loss tends to be more pronounced in people who restrict their carbohydrates to less than 50 grams per day (a very low carb diet), as opposed to those who stick to a low-carb diet which is between 60 and 130 grams of carbohydrates daily. Remember, a standard diet contains about 200 to 300 grams of carbohydrates daily, so a low-carb diet offers a pretty dramatic drop.

It's important to note that one of the interesting, and sometimes discouraging, things about this water is that once gone, it doesn't all stay gone. Returning to eating a higher level of carbohydrate will definitely increase the number of glycogen stores, causing overnight weight gain (but not, of course, fat gain).

But even if you don't go back to eating a lot more carbohydrate, glycogen stores gradually build back up (the glucose mainly coming from gluconeogenesis from protein).

This is not at all a bad thing, as our bodies need to maintain a certain level of blood glucose, and having a reserve is an important "slush fund," so to speak.

But these changes can really do a number on scale-watchers who are anxiously tracking those lost pounds. Even when you are losing fat, those tides of water flowing in and our of your body for this and other reasons create what looks like stalls in your weight loss. The trick is not to get too tied to the scale during this time.

The Second Week of a Low-Carb Diet

It's good to think of the second week as a week of consolidation after the roller coaster metabolism shift of the first week.

You should start feeling more stable, and your appetite should be adjusting. This is often where the real fat loss will start in most people who respond well to low-carb diets. Some bodies do take a little longer to adjust, however, so try to remain patient. 

It's also important during this time to ensure that you are not only reducing your carbohydrate intake but choosing healthy alternatives. For instance, since carbohydrates are found in many fruits, vegetables, grains, dairy products, and alcohol, you will be eating more fats and proteins.

Be sure to choose healthy sources of protein and fats (called  monounsaturated and polyunsaturated fats) like:

  • Avocado
  • Nuts and seeds
  • Olive oil
  • Fish like salmon

Fruits and vegetables are healthy, though you just need to choose low-carb options like: 

  • Broccoli and cauliflower
  • Spinach and kale
  • Bell peppers 
  • Brussel sprouts
  • Asparagus
  • Melons like cantaloupe and watermelon
  • Strawberries

The Third and Fourth Week of a Low-Carb Diet

Sometime in the second half of the first month, your body will probably settle into a pattern of weight loss. The rate at which you lose depends on many factors, the most prominent of which is how overweight you are to start out with. In other words, people with less to lose will lose much more slowly than those with a lot of extra fat.

Generally, once the first couple of weeks are over, people will lose between half a pound and two pounds per week which is considered a healthy rate. The usual advice is to weigh yourself once a week because of day-to-day weight fluctuations due to fluid, fiber consumed, and other factors. Also, women who are having menstrual cycles sometimes decide not to weigh in the second half of their cycles, especially if they tend to retain water at this time.

Finally, it's important to choose a consistent time of day to weigh yourself. Most of the time people choose to weigh first thing in that morning, before beginning to eat and drink, because this is the best basis for comparison. If you weigh yourself at another time of day, there will be even more fluctuations.

After the First Month on a Low-Carb Diet

In a large review study on over 1,000 people with obesity who followed a low-carb diet, the average weight loss was about 15 pounds for people followed between three and six months after beginning the diet. After two years of follow-up, the average weight loss was about 10 pounds; so still a reduction, but this data suggests that people do tend to gain some weight back.

Likewise, there are other scientific studies that suggest a low-carb diet is better for short-term and not long-term weight loss. For instance, one study of over 400 people who were either overweight or obese found that the difference in weight loss at six months (which was higher in people on a low-carb diet as compared to a low-fat diet) was not sustained at the one-year mark. 

In fact, the weight loss at six months in this study was an average of seven pounds on the low-carb diet, so less than the prior study. Again, it's extremely challenging to pinpoint an exact "how many pounds" number, as there are too many other factors at play when it comes to a person's weight.

What does this all mean? It does not predict your individual weight loss (or gain back) but suggests that the diet may be potentially challenging to adhere to for a long time. So like any diet, it's best to choose a way of eating that is healthy and includes food you enjoy, as you will, in the end, be more likely to stick with it.

A Word From Verywell

In the end, if you can manage your weight well with a low-carb diet and do not seem to miss carb-laden foods (for example, bread, rice, and pasta), this diet may be a sensible option for you. But be sure to follow the diet under the guidance of your doctor to ensure it is safe for you.

In addition to weight control, your low-carb manner of eating may have other health benefits too, like lowering your risk of type 2 diabetes and heart disease.

Sources:

Browning JD et al. Alterations in hepatic glucose and energy metabolism as a result of calorie and carbohydrate restriction. Hepatology 48(5):1487-1496. 2008.

Gardner CD et al. Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women. Journal of the American Medical Association 297-9. 2007.

Lennerz BS et al. Effects of dietary glycemic index on brain regions related to reward and craving in men. American Journal of Clinical Nutrition. 98:3 (2013) 641-7.

Santos FL, Esteves, SS, da Costa Pereira A, Yancy WS Jr Nunes JP. Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors. Obesity Reviews. 13:11 (2012) 1048-66.

Shai I et al. Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet."The New England Journal of Medicine 359:229-241. July 17, 2008.

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