Fewer Than 1 in 100 People Need More Than 2.4 Times Their Resting Energy Expenditure | Eating More 'll Make You Fat!

Sweet potatoes alone won't cut it for Tour de France Cyclists and people on a North Pole Expedition - the only study subjects who need >5x their RMR.

I assume you won't have the technical equipment to measure your total energy expenditure by the means of doubly labeled water. Accordingly, I would suggest you go back to my recent article about the accuracy of equations to calculate your resting energy expenditure (read it). Once you know that you multiply it by 2.0-2.4 and that's it: You are not going to expend more energy per day, bro...

How do I know? From a recent paper by Klaas R. Westerterp published in the Proceedings of the Nutrition Society (2017). In the paper, he reviewed results from doubly labeled water studies of the total daily energy expenditure (TDEE) under daily living conditions.
The goal was to determine the ratio of total daily energy expenditure to the resting metabolic rate, a quantity scientists somewhat misguidingly call the physical activity level (PAL). Since the carbon dioxide production needs interpretation as it critically depends on your substrate utilization (21·1 kJ/l CO2 for carbohydrate oxidation vs. 27·8 kJ/l for CO2 fat oxidation) and can not be 100% accurate unless all relevant dietary information is available.

While the energy equivalent is 23·5 kJ/l for subjects consuming a typical Western diet with 55 % carbohydrate, 15 % protein, and 30 % fat, exercising subjects often consume diets with a large contribution of carbohydrate-rich sports drinks. Accordingly, they will have a correspondingly lower value for the energy equivalent of carbon dioxide of 23·0 kJ/l. As Westertarp points out, "[i]n he Tour de France, the contribution of sports drinks was twice as high, resulting in an energy equivalent of 22·5 kJ/l carbon dioxide" (Westerterp 2017).

Figure 1. Pal value distribution in the general population in men (grey) and women (white) bars as measured in the first two-week doubly-labeled water analysis (left); PAL values decline from age 50+ almost linearly in both older men (dotted line) and older women (solid line | Westerterp 2017).

That does not change the fact that for the average population less than 1% achieve PAL values beyond the 2·00–2·40 of 'high expenders'. What does that mean? Well, if your RMR is 1600kcal, you better be competing in the Tour de France if you want to get away with eating significantly more than 3840kcal per day (note: if you do only slow-paced classic resistance training you won't even get close to that value - any gains you make with 2.4x your RDA will at least in large parts body fat).
And no, these values were not observed while dieting. If food intake is restricted, the exercise induced increase in energy expenditure will decrease even further. Plus: The review also shows that "an exercise induced increase in activity energy expenditure can be compensated by a reduction in REE and by a reduction in non-exercise physical activity - especially at a negative energy balance. So...

• you are not going to need more than 2.0-2.4x your RDA per day - unless you're really competing in the Tour de France (see information in the previous red box).
• if you try to surpass this limit by exercising, even more, your resting energy expenditure will decrease (478,011kcal more than the reduction in weight would suggest in Johannsen (2012).

Additionally, in untrained subjects, an exercise-induced increase in activity energy expenditure is compensated by a training-induced increase in exercise efficiency. Which means that

• the more trained you are the less energy you will need for the same amount of exercise

As the data in Figure 1 goes to show you, women are on average less active than men, but their numbers in the high activity group is still higher.

What does previous research say?

Westerterp found only 10 studies that utilized the measurement of PAL to assess the effect of exercise before and during an exercise intervention. The exercise interventions, which lasted for 4-40 weeks, used either aerobic training or resistance training, and were with two to five 40–90 min sessions per week, representative of the physical activity the average gymrat may be accumulating. In view of the fact that all subjects had been sedentary slobs before the intervention, the significance of the measured PAL values of 1·40–1·69 is not clear.

Figure 2: Participating in a half-marathon training will "at best" get you across to the 2.0 PAL mark (Westerterp 1992)

In four of those studies, subjects reached values of 2·00–2·40 for a vigorously active lifestyle, but that required absolutely unrestricted energy intakes. Interestingly enough, the only study that combined exercise interventions with an energy-restricted diet, the extra exercise did not increase the ratio of the total to the resting energy expenditure in the 20 healthy obese women who participated. In none of the ten studies, PAL values over the 2.0-2.4 maximum were reached.

One of the reasons why exercise intervention could fail to improve the PAL values is that people compensate by reducing non-exercise physical activity significantly. Scientific evidence to support this assumption has yet only been observed in studies in elderly individuals and studies that combined exercise with energy restriction.
References:

• Johannsen, Darcy L., et al. "Metabolic slowing with massive weight loss despite preservation of fat-free mass." The Journal of Clinical Endocrinology & Metabolism 97.7 (2012): 2489-2496.
• Westerterp, K. R., et al. "Use of the doubly labeled water technique in humans during heavy sustained exercise." Journal of Applied Physiology 61.6 (1986): 2162-2167.
• Westerterp, Klaas R., et al. "Long-term effect of physical activity on energy balance and body composition." British Journal of Nutrition 68.1 (1992): 21-30.