Published: 09/16/2015

Four Reasons for Stalled Weight Loss

By Jeff S. Volek, Ph.D., R.D.

When one of your patients experiences stalled weight loss, rule out noncompliance, “carb creep” and the other possibilities before assuming it is an actual plateau, the inexplicable cessation of weight loss that continues for more than a month. Here are four other possible reasons why this may be happening.

Reason 1: Water Weight

The body is approximately 60 percent water, and muscles and some other tissues are closer to three-fourths H2O.. For a 200-pound guy, that means he is carrying around about 120 pounds of fluid. That water makes up the majority of the blood, and gives  cells shape and a fluid medium to bathe in. The body works hard to maintain a delicate balance of water distribution while accounting for its intake and excretion. That system varies a couple of percent points up or down depending on a variety of factors, such as menstrual phase, fluid and electrolyte intake, plus exercise.

A 1.5 percent variation in those 120 pounds of water accounts for 1.8 pounds. So the 200-pound patient’s water weight could swing nearly 4 pounds between 118.2 to 121.8 pounds, depending on when he gets on the scale. That’s why we highly recommend weight averaging and monitoring one’s weight loss trajectory over several weeks or months to get an accurate weight loss picture. This natural variation is also why we advise against a daily weigh. 

Some people are more sensitive to fluctuations in water weight than others. When an individual exercises for the first time or tries a new form of physical activity, the muscle fibers can become swollen and inflamed, causing a temporary water imbalance. That swelling stimulates pain receptors and contributes to the delayed onset of sore muscles, which usually peaks 12 to 48 hours after exercise. The soreness and swelling are transient, and fortunately the body remembers, so when the person exercises again the inflammation and swelling are considerably less. 

Reason 2: Fat Is Less Dense Than Muscle

Fat and muscle have different densities, and therefore vary in volume. In other words, fat takes up more space than an equal amount of muscle. The approximate density of muscle is 1.06 grams (g) per cubic centimeter (cc), compared to fat, which has a density of 0.9 g/cc. So given equal amounts, muscle takes up 18 percent less space than fat. That’s why two people who weigh the same can look very different, depending on how much fat and muscle each has. This is also why patients should evaluate their progress by inches lost, how clothes fit and which notch they use on their belt rather than just relying on the scale. 

Relative density can also explain why weight loss might slow or stall if a person starts exercising—or increases the intensity or duration of an existing program. If resistance training is added, muscle might be accumulating while body fat is being lost, which is great—but could translate to slower weight loss. That’s no reason to stop the exercise. Resistance training protects muscle but doesn’t impede fat loss. 

Reason 3: Weight Loss Is Not Linear

Most of the body’s processes don’t proceed in a straight line. Rather, the body tends to alternate between rapid and slow phases or—in some cases—takes quantum leaps. A good example is the teen-age growth spurt when kids may shoot up as much as 3 to 4 inches in one school year. Many examples, such as wound healing, blood clotting, glycogen synthesis, hormone secretion and development of atherosclerosis, also progress in a non-linear time pattern. Weight loss is no exception. The adage “two steps forward, one step back” is apt in this case. Regardless of some of the explanations above, a stall in weight loss could simply be the body’s natural course. In most cases, the temporary plateau or step backward will switch directions as long as long as the person stays the course. 

Reason 4: Approaching Goal Weight

As an individual gets closer to his or her target weight, the body starts to defend against further weight loss. If someone has 50 pounds to lose, the first 30 or 40 tend to come off relatively easily because the goal weight is still relatively far off. That last 10 to 20 pounds will usually take longer, and require more discipline, as the body senses the approach of its natural weight. The key is to be patient and let fat burning do its thing. 

For more on stalled weight loss, see How to Handle a Plateau

Jeff S. Volek is a member of the Atkins Science Advisory Board and one of the authors of The New Atkins for a New You.