Starvation Mode: Fact or Fiction?

Starvation-mode (or starvation-response) is the popular theory that the body “reacts” to dieting by lowering its metabolic rate in order to preserve itself. According to the theory a dieter could be following a reduced-calorie eating plan—to the letter—and still not lose an ounce. Furthermore, the purported solution is that one needs to eat more in order to lose weight.

The theory is an attempt to explain why people aren’t losing weight although they report (to their weight loss coach, or fellow dieters) that they are indeed following their diet and exercise program.

What are the problems with the theory?

Metabolic rates don’t actually drop enough to significantly slow weight loss (if someone is indeed adhering to a reduced-calorie target). There can be a small reduction in (resting) metabolic rate when you reduce your calorie intake. For most people—since they're eating 1,200 or more calories per day—that drop won’t be more than 5%. For the minority of people that eat fewer calories (which should only occur under medical supervision) the reduction may be 5- to 15%.[i] In neither case will weight loss STOP, or stall, beyond what’s explainable by those changes. Under no circumstances will EATING MORE be necessary. Not everyone will experience this reduction in metabolism, but for those that do it dissipates a week or so after they resume a calorie intake level that matches (or exceeds) the physiolgical needs of their current body weight.[ii]

Studies of “diet-resistant” subjects consistently find normal metabolic rates, AND underreporting of calorie intake. There are four studies on obese subjects who were referred to metabolic labs for further analysis because they were not losing weight while reporting energy intakes that should have been resulting in weight loss of 1- to 2-pounds per week. In each case (other than 2 subjects with hypothyroid status) all subjects among these three studies were found to have metabolic rates within the normal range—no starvation mode happening—and to be simply underreporting their energy intake. [iii]^{,[iv],[v],[x]} 

Subjects underreported by an average of 1,453 calories per day in the study by Buhl, by 1,000 calories per day in the study by Skov, and by 1,053 calories per day in the study by Lichtman. The hypothyroid subjects also underreported by 800 to 900 calories per day. In the study by Heymsfield, where subjects underreported by an average of almost 1,200-calories per day, he discusses potential causes of underreporting of energy intake including: inadequate calorie knowledge, inaccurate portion estimates, memory disturbance (forgetting), inaccurate food labeling, and psychosocial motivation (conscious or not).

Heymsfield was able to show in his patient group however, that the same subjects were able to accurately report, "when they believed the researcher would be able to check the accuracy of their reporting," which apparently supported psychosocial motivation. To explore that further the study subjects (and a control group) were administered the Minnesota Multiphasic Personality Inventory. The subjects scored significantly higher than controls in key areas, confirming the tendency toward both conscious impression management (the purposeful tailoring of one's responses to display a positive image to others), and unconscious self-deception (described as the tendency to distort information to preserve a more virtuous self image [in this case, as a stringent dieter]).

Clearly, underreporting of energy intake is a complicated phenomenon. What we do know for sure it that it's a widespread problem, and while it occurs across all BMI groups the degree of underreporting also increases as BMIs increase.

Research looking at chronically undernourished populations has also failed to find evidence supporting starvation mode.[vi]^{,[vii],[viii]}

Despite widespread anecdotal reports of problems with starvation mode, there isn’t a single published case study documenting an individual in starvation mode in the medical literature. Apparently medical science has yet to find a person that doesn’t lose weight (as expected by the 1^st Law of Thermodynamics) when underfed. Should we be surprised that—like GRAVITY—this law of physics applies to everybody?

The starvation mode theory certainly is appealing from the standpoint that it lets both the dieter and their coach off the hook—lack of progress is blamed on something out of the dieters' control.[ix] It’s a sad situation however, after all, there is nothing to problem-solve if you believe your body is betraying you. No path forward. On the the other hand, some may find playing the martyr rewarding (consciously or not); there's a lot of attention to be gained and that attention reinforces the pattern unless it challenges it. 

The Bottom Line: Given the laws of physics, the notion that some people need to eat more to kick start weight loss is inherently flawed. Starvation mode is simply VERY popular mythology. Carefully tracking your calorie intake and exercise can actually reinforce that your body works just as it should. See the advise at the end of my blog on weight loss plateaus for more suggestions. Having your metabolic rate measured can also give you peace of mind. You can trust that:

• Positive energy balance leads to weight gain
• Negative energy balance leads to weight loss, and
• Only neutral energy balance supports a stable weight

All the Best,
-Dorene

Related articles:
Normal Range of Metabolism
How Dieting Affects Your Metabolic Rate
Myth: Yo-yo Dieting Ruins Your Metabolism
How to Lose Weight 101: Understanding Energy Balance

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[i] Poehlman ET, et al. The Impact of Exercise and Diet Restriction on Daily Energy Expenditure. Sports Med. 1991;11:78-101.

[ii] Weinsier RL, et al. Do Adaptive Changes in Metabolic Rate Favor Weight Regain in Weight-Reduced Individuals? An Examination of the Set-Point Theory. Am J Clin Nutr. 2000;72:1088-1094.

[iii] Heymsfield SB, et al. The calorie: myth, measurement and reality. Am J Clin Nutr 1995;62(suppl):1034s-41s.

[iv] Skov AR, et al. Normal levels of energy expenditure in patients with reported "low metabolism." Clinical Physiology 1997;17:279-285.

[v] Buhl KM Unexplained disturbance in body weight regulation: diagnostic outcome assessed by doubly labeled water and body composition analyses in obese patients reporting low energy intakes. J Am Diet Assoc 1995;95:1393-1400.

[vi] Soares MJ, et al. Basal metabolic rates and metabolic efficiency in chronic undernourished. Euro J Clin Nutr. 1991;45:363-373.

[vii] Shetty PS. Chronic undernutrition and metabolic adaptation. Proceedings of the Nutrition Society. 1993;52:267-284.

[viii] Ferro-Luzzi A, et al. Basal metabolism of weight-stable chronically undernourished men and women: lack of metabolic adaptation and ethnic differences. Am J Clin Nutr 1997;66:1086-93.

[ix] The Starvation Myth

[x] Lichtman SW, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. NEJM 1992;327(27):1893-1898. 

[x] Tremblay A, et al. Energy requirements of a postobese man reporting a low energy intake at weight maintenance. Am J Clin Nutr 1991:54:506-508.