Would a person with high body fat survive longer without food?

Question

Considering the following information:

The more fat stores available, the longer a person can typically survive during starvation. Once the fat stores have been completely metabolized, the body then reverts back to muscle breakdown for energy, since it’s the only remaining fuel source in the body. - https://www.healthline.com/health/food-nutrition/how-long-can-you-live-without-food.

Pure fat has a very high energy content, or about 9 calories per gram. - https://www.healthline.com/nutrition/calories-in-a-pound-of-fat.

As a general rule, people need a minimum of 1,200 calories daily to stay healthy. - https://www.everydayhealth.com/weight/can-more-calories-equal-more-weight-loss.aspx.

Would a person with higher body fat survive longer without food compared to someone with a healthy weight, considering there is sufficient access to water. Could the body fat also theoretically be used to determine the weight loss rate of roughly 134grams (about 1,200 calories) per day considering minimal but consistent activity, normal functioning of organs and consistent water intake and secretion. Is my assumption correct that if there is sufficient excess body fat, and water and the person is overall healthy that it's more likely to die from a lack of nutrients such as vitamins and minerals than from lack of food?

Would it be possible to roughly calculate the starvation rate (days) based on fat percentage? Also, side-question: Where would the body get nutrients such as vitamins? Are for example the fat-soluble vitamins A, D, E, and K stored and accessible from the stored body fat?

Answer 1

Scientific studies of individuals who have died of starvation are thankfully uncommon. However, an analysis of the literature published in 2001 provides evidence of a sort of "minimum BMI" required to sustain human life.

A BMI below 13 in males and 11 in females may be the lowest limit compatible with life.

In that regard, all other things being equal, it would seem that someone who starts at a higher BMI would take longer to reach that threshold. However:

The loss of bodyweight represents the utilization of body tissues as an energy source. However, the relationship between energy deficit and weight loss is not a simple one. Several factors, such as degree of adiposity, level of hydration, [and] sex of the individual... influence weight loss.

While there are starting and ending weights and fast durations presented in the paper that could theoretically calculate the rate of loss, individual factors are likely to make such calculations of minimal utility.

Another study describes complications which may result in death unrelated to lack of energy:

Of the five individuals monitored closely, one developed symptomatic hypokalaemia, which eventually needed intravenous rectification. This individual went on to develop acute Werneke’s encephalopathy.

Dysregulated thyroid hormone metabolism is also mentioned. Overall, among individuals with starting higher BMI, they are likely to experience significant electrolyte disturbances with only access to plain water. These may result in death sooner (potentially by fatal arrhythmia), though vitamins are also clearly an issue.