Nowadays, Smart Environments (SEs) enable the monitoring of people with physical disabilities by incorporating activity recognition. Thermal cameras are being incorporated as they preserve privacy. Some Deep Learning (DL) solutions use the pose of the users because it removes external noise. Although there are robust DL solutions in the visible spectrum, they fail in the thermal domain. Thus, we propose THPoseLite (Thermal Human Pose Lite), a Convolutional Neural Network (CNN) based on MobileNetV2 that extracts pose from Thermal Images (TIs). In a novel way, an auto-labeling approach has been developed. It includes a background removal using an optical flow estimator. It also integrates Blazepose (a pose estimator for Visible spectrum images (VSIs)) to obtain the poses in the pre-processed TIs. Results show that the pre-processing increases the percentage of detected poses by Blazepose from 19.55% to 76.85%. This allows the recording of Human Pose Estimation (HPE) datasets in the visible spectrum without requiring visible spectrum cameras or manually annotating datasets. Furthermore, THPoseLite has been embedded in an Internet of Things (IoT) device incorporating an edge Tensor Processing Unit (TPU) accelerator, which can process TIs recorded at 9 Frames Per Second (FPS) in real-time (12.28 FPS). It requires fewer than 6W of energy to run. It has been achieved using model quantization, decreasing the accuracy in estimating the poses by only 1%. The MSE of MobileNetV2 in test images is 35.48, obtaining accurate poses in 21% of the images that Blazepose is not able to detect any pose.